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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
OFFSET
1,1
COMMENTS
Corresponding centered pentagonal primes are listed in A145838 = {31, 181, 331, 601, 1051, 1381, 3331, ...}.
LINKS
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
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