A077003 - OEIS

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A077003

a(n)= index of triangular number A077002(n).

1, 1, 1, 2, 4, 9, 22, 59, 167, 501, 1585, 5258, 18215, 65676, 245738, 951740, 3806961, 15696503, 66594623, 290279233, 1298168196, 5948954024, 27903067710, 133818411722, 655573653819, 3277868269096, 16713914267109, 86848046111951 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,4`
	LINKS	`Table of n, a(n) for n=1..28.`
	MAPLE	`a[1] := 1:b[1] := 1:for n from 2 to 100 do a[n] := floor(evalf(-1/2+1/2sqrt(1+8(n-1)a[n-1])+1/10^50, 300)):b[n] := a[n]:a[n] := a[n](a[n]+1)/2:od:seq(b[l], l=1..100);`
	CROSSREFS	`Cf. A077002.` `Sequence in context: A177377 A035053 A000571 * A210726 A046917 A187044` `Adjacent sequences: A077000 A077001 A077002 * A077004 A077005 A077006`
	KEYWORD	`nonn`
	AUTHOR	`Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Oct 26 2002`
	EXTENSIONS	`More terms from Sascha Kurz, Jan 26 2003`
	STATUS	`approved`

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Last modified May 21 16:07 EDT 2013. Contains 225504 sequences.