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A015507 a(1)=1, a(n) = sum_{k=1}^{k=n-1} (6^k-1)/5 a(k). 0
1, 1, 8, 352, 91520, 142405120, 1328924579840, 74403829376081920, 24994031979330942894080, 50376471215620688640734003200, 609214555257707874214915513922355200, 44204249911340791820804231319883906967142400 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..12.

FORMULA

a(n) = ((6^(n-1) + 4)/5) * a(n-1). - Vincenzo Librandi, Nov 12 2012

PROG

(MAGMA) I:=[1, 1, 8]; [n le 3 select I[n] else ((6^(n-1) + 4)/5) * Self(n-1): n in [1..15]]; // Vincenzo Librandi, Nov 12 2012

CROSSREFS

Sequence in context: A221044 A221163 A000436 * A167256 A277656 A264198

Adjacent sequences:  A015504 A015505 A015506 * A015508 A015509 A015510

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified May 22 09:12 EDT 2022. Contains 353941 sequences. (Running on oeis4.)