id:A039835 - OEIS Search Results

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Indices of triangular numbers which are also heptagonal.

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3

1, 10, 493, 3382, 158905, 1089154, 51167077, 350704366, 16475640049, 112925716858, 5305104928861, 36361730124070, 1708227311453353, 11708364174233842, 550043889183050965, 3770056902373173214 (list; graph; listen)

	OFFSET	`1,2`
	LINKS	`Eric Weisstein's World of Mathematics, Link to a section of The World of Mathematics.`
	FORMULA	`G.f.: (-2x^4-9x^3+161x^2+9x+1)/[(1-x)(1-18x+x^2)(1+18x+x^2)].` `a(n+2)=322a(n+1)-a(n)+160 a(n+1)=161a(n)+80+36(20a(n)^2+20*a(n)+9)^0.5 - Richard Choulet (richardchoulet(AT)yahoo.fr), Sep 29 2007`
	CROSSREFS	`Cf. A046193, A046194.` `Cf. A046194 A046193.` `Sequence in context: A159533 A035320 A071096 this_sequence A127947 A095232 A042209` `Adjacent sequences: A039832 A039833 A039834 this_sequence A039836 A039837 A039838`
	KEYWORD	`nonn`
	AUTHOR	`Eric Weisstein (eric(AT)weisstein.com)`

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Last modified December 4 23:11 EST 2009. Contains 170347 sequences.

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