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A145837 Indices of primes in A005891(n). 0
3, 8, 11, 15, 20, 23, 36, 44, 47, 48, 60, 68, 71, 75, 83, 84, 87, 92, 111, 116, 128, 132, 143, 144, 156, 159, 164, 167, 168, 183, 192, 200, 204, 207, 215, 224, 228, 231, 236, 239, 264, 272, 287, 299, 300, 303, 312, 315, 320, 323, 356, 359, 360, 363, 372, 387 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Corresponding centered pentagonal primes are listed in A145838 = {31, 181, 331, 601, 1051, 1381, 3331, ...}.

LINKS

Table of n, a(n) for n=1..56.

Eric Weisstein's World of Mathematics, Centered Pentagonal Number

FORMULA

A005891(a(n)) = A145838(n)

MATHEMATICA

(Position[LinearRecurrence[{3, -3, 1}, {1, 6, 16}, 400], _?PrimeQ]// Flatten)-1 (* Harvey P. Dale, Sep 08 2018 *)

CROSSREFS

Cf. A145838 = Primes in A005891. Cf. A005891 = Centered pentagonal numbers: (5n^2+5n+2)/2.

Sequence in context: A234431 A310282 A081858 * A111132 A188473 A003234

Adjacent sequences:  A145834 A145835 A145836 * A145838 A145839 A145840

KEYWORD

nonn

AUTHOR

Alexander Adamchuk, Mar 21 2009

EXTENSIONS

Extended by R. J. Mathar, Mar 26 2009

Edited by N. J. A. Sloane, Apr 06 2009

STATUS

approved

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Last modified May 12 06:30 EDT 2021. Contains 343814 sequences. (Running on oeis4.)