A231279 a(n) = Jacobsthal(n^2), where Jacobsthal(n) = A001045(n).

0, 1, 5, 171, 21845, 11184811, 22906492245, 187649984473771, 6148914691236517205, 805950546409752783137451, 422550200076076467165567735125, 886151997189943915269204706853563051, 7433581732843541047178572757549453835326805, 249429612771140764706762211450245635354612487334571

Offset

0,3

Links

Table of n, a(n) for n=0..13.

Formula

a(n) = (2^(n^2) - (-1)^n) / 3.

One-third the logarithmic derivative of A211892.

Maple

a:= n-> round(2^(n^2)/3):
seq(a(n), n=0..13);  # Alois P. Heinz, May 23 2026

Prog

(PARI) {a(n)=(2^(n^2)-(-1)^n)/3}
for(n=1, 15, print1(a(n), ", "))

Crossrefs

Cf. A001045, A211892, A083228, A231292.

Sequence in context: A326555 A279382 A157234 * A210832 A206393 A220640

Adjacent sequences: A231276 A231277 A231278 * A231280 A231281 A231282

Keyword

nonn

Author

Paul D. Hanna, Nov 06 2013

Extensions

a(0)=0 prepended by Alois P. Heinz, May 23 2026

Status

approved