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A015489 a(0)=1, a(1)=4, a(n) = sum_{k=0}^{k=n-1} 4^k a(k). 0
1, 4, 17, 289, 18785, 4827745, 4948438625, 20273753046625, 332185443668950625, 21770437421732017110625, 5707011317919939625464790625, 5984240806710536532650993759190625 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Table of n, a(n) for n=0..11.

FORMULA

a(n) =  (4^(n-2) + 1) * a(n-1). - Vincenzo Librandi, Nov 11 2012

PROG

(MAGMA) I:=[1, 4, 17]; [n le 3 select I[n] else (4^(n-2)+1)*Self(n-1): n in [1..15]]; // _Vincenzo Librandi, Nov 11 2012

CROSSREFS

Sequence in context: A214143 A320986 A302145 * A153061 A277762 A337477

Adjacent sequences:  A015486 A015487 A015488 * A015490 A015491 A015492

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard

STATUS

approved

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Last modified August 15 12:09 EDT 2022. Contains 356145 sequences. (Running on oeis4.)