64 AD., Nero, Balkan mint (Perinthos ?), Sestertius, unlisted, cf. RIC I, p. 186-7.

Nero, Balkan mint (Perinthos ?), ca. 64 AD. (?),
Æ Sestertius (ø 33-35 mm / 24,68 g), brass ("orichalcum"), axes irregular alignment ↑↙ (ca. 230°),
Obv.: NERO CLΛYDIVS CΛESΛR AVG GEKM IM TPΛ IMP [P P?] , his laureate head facing right, clear dimple on cheek, in parts Greek letter style (Y for V, Λ for A), spelling errors.
Rev.: DECVRSIΘ / S - C , Nero, bare-headed and in military attire, prancing r. on horseback, holding spear with r. hand; behind him, mounted soldier prancing r. with vexillum held over r. shoulder; DECVRSIΘ in ex., S - C flanking in fields; weak dimple on horse just above emperor´s knee; spelling error Θ for O.
unlisted, cf. RIC I, p. 186-7 ; cf. RPC I, p. 320, nos. 1758-62 ; RPC consolidated supplement 1-3, - ; online available databases - .
for a similar coin cf. http://www.forumancientcoins.com/board/index.php?topic=98790.0 .

The dimple on both sides, Greek letter style (Y for V, Λ for A, Θ for O), spelling errors plus the irregular alignment suggested a Balkan mint. All the Latin coins of Perinthus are rare. BMC does not list Perinthus mint, but identifies a similar type as "barbrous". RIC notes the existence of Balkan sestertii, dupondii and asses but does not catalog them.

Curtis Clay on http://www.forumancientcoins.com/board/index.php?topic=36254.0 :
"Basemetal's sestertius, with centration dimples, was struck at a branch mint in Thrace. Coins of this mint were little known before coins began flooding out of Bulgaria and Romania with the fall of the Iron Curtain. I wonder if any from this mint were included in Kleiner's die corpus of Arch sestertii of Nero."

Curtis Clay on http://www.forumancientcoins.com/board/index.php?topic=76755.0 :
"Since the series was only recognized by MacDowall in Num. Chron. 1960, but most of the known specimens have only emerged from the Balkans after 1990, the series is abysmally catalogued in the standard references.
Sutherland in his new RIC (1984), pp. 186-7, merely summarizes MacDowall's findings without listing the coins individually.
RPC I (1992), 1759-1762, appeared too early to take account of the new flood of material from the Balkans, so mainly merely repeats the few varieties known to MacDowall, with MacDowall's illustrations too for the most part.
Little was added in RPC Suppl I, 1998, p. 24, and Supplement 2, Part 1, 2006 (online), p. 39.
My own assemblage of material appearing after 1990 has been haphazard, so not thorough or systematic."