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A354984
Numbers that are 3 * prime powers congruent to 1 (mod 3).
4
12, 21, 39, 48, 57, 75, 93, 111, 129, 147, 183, 192, 201, 219, 237, 291, 309, 327, 363, 381, 417, 453, 471, 489, 507, 543, 579, 597, 633, 669, 687, 723, 768, 813, 831, 849, 867, 921, 939, 993, 1011, 1029, 1047, 1083, 1101, 1119, 1137, 1191, 1227, 1263, 1299, 1317, 1371, 1389, 1461, 1497, 1569, 1587, 1623, 1641, 1713
OFFSET
1,1
COMMENTS
Numbers k of the form 9m+3 such that k/3 = p^k, with p a prime and k >= 1.
FORMULA
a(n) = 3 * A137827(n).
MATHEMATICA
Select[Range[2000], Mod[#, 9] == 3 && PrimePowerQ[#/3] &] (* Amiram Eldar, Jun 15 2022 *)
PROG
(PARI)
A354983(n) = ((3==(n%9)) && isprimepower(n/3));
isA354984(n) = A354983(n);
CROSSREFS
Intersection of A017197 and 3*A246655.
Cf. A137827, A354983 (characteristic function).
Row 3 of A354930 (conjectured).
Sequence in context: A325301 A351478 A219542 * A367357 A137480 A316267
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 15 2022
STATUS
approved