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A332985 Index of triangular numbers that are sum of two pentagonal numbers (A332984). 2
3, 4, 8, 14, 32, 34, 41, 42, 46, 47, 49, 53, 58, 63, 66, 67, 69, 71, 76, 79, 82, 86, 89, 90, 100, 101, 102, 110, 113, 117, 124, 129, 141, 151, 159, 168, 175, 178, 183, 186, 192, 195, 205, 216, 217, 219, 232, 241, 247, 250, 252, 253, 255, 258, 261, 263, 265, 271, 284, 293, 297, 298 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

The index of a triangular number T is the integer n such that T = n*(n+1)/2.

LINKS

Peter Kagey, Table of n, a(n) for n = 1..1000

CROSSREFS

Cf. A000217 (triangular numbers), A000326 (pentagonal numbers), A332987 (sums of two nonzero pentagonal numbers).

Sequence in context: A049866 A118355 A026632 * A026654 A104370 A310013

Adjacent sequences:  A332982 A332983 A332984 * A332986 A332987 A332988

KEYWORD

nonn,easy

AUTHOR

Olivier Gérard, Mar 05 2020

STATUS

approved

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Last modified May 24 23:45 EDT 2020. Contains 334581 sequences. (Running on oeis4.)