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A077003 a(n)= index of triangular number A077002(n). 1
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+1/2*sqrt(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: A321994 A035053 A000571 * A210726 A046917 A237770

Adjacent sequences:  A077000 A077001 A077002 * A077004 A077005 A077006

KEYWORD

nonn

AUTHOR

Amarnath Murthy, Oct 26 2002

EXTENSIONS

More terms from Sascha Kurz, Jan 26 2003

STATUS

approved

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Last modified June 25 17:47 EDT 2019. Contains 324353 sequences. (Running on oeis4.)