A083517 - OEIS

A083517

Triangular numbers which are one more than a product of distinct triangular numbers.

91, 136, 946, 1081, 1711, 1891, 2701, 5671, 7021, 8911, 10585, 11935, 13861, 14365, 18145, 19306, 21736, 25651, 26335, 29161, 32131, 36856, 41041, 44551, 49141, 55945, 64261, 65341, 69751, 70876, 82621, 92665, 93961, 106030, 107416, 108811

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OFFSET

1,1

LINKS

Andrew Howroyd, Table of n, a(n) for n = 1..341

EXAMPLE

91 = 6*15 + 1, 1081 = 3*10*36 + 1.

PROG

(PARI) upto(lim)={my(v=[1]); for(k=2, oo, my(t=k*(k+1)/2); if(t\3>lim, break); my(s=(lim-1)\t); v=setunion(v, t*select(j->j<=s, v))); [j+1 | j<-v, ispolygonal(j+1, 3)]} \\ Andrew Howroyd, Sep 21 2024

CROSSREFS

Cf. A000217.

Sequence in context: A353062 A260974 A020301 * A088983 A045934 A051347

Adjacent sequences: A083514 A083515 A083516 * A083518 A083519 A083520

KEYWORD

nonn

AUTHOR

Amarnath Murthy and Meenakshi Srikanth (menakan_s(AT)yahoo.com), May 05 2003

EXTENSIONS

Corrected and extended by David Wasserman, Nov 19 2004

Offset changed by Andrew Howroyd, Sep 21 2024

STATUS

approved