A068532 a(n) = (5^(2^n)-1)/(3*2^(n+2)).

1, 13, 4069, 794728597, 60632980118195215861, 705860789378583615890268750566368301709493, 191323950329148357416786545771849882457465097130873620037231723027086142489376167456309

Offset

1,2

Links

Table of n, a(n) for n=1..7.

Formula

a(n+1)/a(n) = (1/2)*A199591(n). - Peter Bala, Feb 16 2026

Mathematica

a[n_] := (5^(2^n)-1)/(3*2^(n+2)); Array[a, 7] (* Amiram Eldar, May 07 2025 *)

Crossrefs

Cf. A068531, A097421, A199591, A359500.

Sequence in context: A070905 A180768 A330905 * A182348 A094316 A270068

Adjacent sequences: A068529 A068530 A068531 * A068533 A068534 A068535

Keyword

easy,nonn

Author

Benoit Cloitre, Mar 22 2002

Status

approved