

A135435


a(n) = a(n4) + a(n7) with a(0), ..., a(6) = [7,0,0,0,4,0,0].


2



7, 0, 0, 0, 4, 0, 0, 7, 4, 0, 0, 11, 4, 0, 7, 15, 4, 0, 18, 19, 4, 7, 33, 23, 4, 25, 52, 27, 11, 58, 75, 31, 36, 110, 102, 42, 94, 185, 133, 78, 204, 287, 175, 172, 389, 420, 253, 376, 676, 595, 425, 765, 1096, 848, 801, 1441, 1691, 1273, 1566, 2537, 2539, 2074, 3007, 4228
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OFFSET

0,1


COMMENTS

Of interest because {7,11} is the earliest pair of typical primes belonging to a single hexad. Herein "pseudoprime" means sequencespecific psp. (i.e. dividing its term with rem. 0), not general numbertheoretic psp. The only psp.s of concern, from the standpoint of primality testing, being those congruent to 1 or 5 (mod 6), are the six quadratics of the present zerotermed primes 5,13,17 the only relevant psp.s of this sequence? Or are there additional examples > 289?


LINKS

G. C. Greubel, Table of n, a(n) for n = 0..1000
Index entries for linear recurrences with constant coefficients, signature (0, 0, 0, 1, 0, 0, 1).


FORMULA

G.f.: (73*x^4)/(1x^4x^7).  R. J. Mathar, Oct 24 2009


MATHEMATICA

LinearRecurrence[{0, 0, 0, 1, 0, 0, 1}, {7, 0, 0, 0, 4, 0, 0}, 70] (* Harvey P. Dale, Jan 20 2013 *)


PROG

(PARI) Vec((73*x^4)/(1x^4x^7) + O(x^80)) \\ Michel Marcus, Oct 14 2016


CROSSREFS

Cf. A133394.
Sequence in context: A229658 A306755 A005070 * A171917 A198919 A019933
Adjacent sequences: A135432 A135433 A135434 * A135436 A135437 A135438


KEYWORD

easy,nonn


AUTHOR

G. Reed Jameson (Reedjameson(AT)yahoo.com), Dec 13 2007, Dec 16 2007


EXTENSIONS

More terms from R. J. Mathar, Oct 24 2009


STATUS

approved



