login
A354981
a(n) = 1 if n = 2 * p^k, with p an odd prime and k >= 1, otherwise 0.
1
0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1
OFFSET
1
FORMULA
a(n) = [n == 2 (mod 4)] * A069513(n/2), where [ ] is the Iverson bracket.
For n > 4, a(n) = A211487(n) - A174275(n).
MATHEMATICA
a[n_] := If[IntegerExponent[n, 2] == 1 && PrimePowerQ[n/2], 1, 0]; Array[a, 100] ( * Amiram Eldar, Jun 15 2022 *)
Module[{nn=150, c}, c=Union[Flatten[Table[2 p^k, {p, Prime[Range[2, 35]]}, {k, 5}]]]; Table[If[ MemberQ[ c, k], 1, 0], {k, nn}]] (* Harvey P. Dale, Sep 18 2023 *)
PROG
(PARI) A354981(n) = (2==(n%4) && isprimepower(n/2));
CROSSREFS
Characteristic function of A278568 \ {2}.
Sequence in context: A361463 A104853 A358775 * A231600 A347579 A280710
KEYWORD
nonn
AUTHOR
Antti Karttunen, Jun 15 2022
STATUS
approved