A139117 - OEIS

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A139117

Triangular numbers (A000217) with indices A000043.

0

3, 6, 15, 28, 91, 153, 190, 496, 1891, 4005, 5778, 8128, 135981, 184528, 818560, 2427706, 2602621, 5176153, 9046131, 9783676, 46943205, 49416711, 62871291, 198751953, 235477551, 269340445, 990013753, 3718970646, 6105511756, 8718535225, 23347768186, 286403014380

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OFFSET

1,1

LINKS

Table of n, a(n) for n=1..32.

FORMULA

a(n) = A000217(A000043(n)).

EXAMPLE

a(4) = 28 because A000043(4) = 7 and the 7th triangular number A000217(7) is 28.

CROSSREFS

Cf. A000217, A000396, A034953.

Sequence in context: A034953 A086737 A063834 * A226736 A066708 A034464

Adjacent sequences: A139114 A139115 A139116 * A139118 A139119 A139120

KEYWORD

nonn

AUTHOR

Omar E. Pol, May 08 2008

STATUS

approved