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A225787 Least prime number p such that p*triangular(n) is a triangular number, or 0 if no such p exists. 1
2, 3, 2, 11, 19, 3, 5, 0, 71, 23, 109, 131, 17, 181, 2, 239, 271, 307, 0, 379, 3, 13, 127, 61, 67, 163, 701, 47, 811, 97, 37, 991, 0, 31, 0, 79, 83, 0, 41, 7, 0, 191, 37, 0, 5, 83, 541, 251, 2351, 613, 71, 0, 0, 2861, 743, 3079, 3191, 367, 0, 3539, 229, 0, 977, 0, 4159 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

LINKS

Table of n, a(n) for n=0..64.

FORMULA

a(n) <= n^2 + n + 2.  For n>0, a(n) <= n^n + n + 1.

EXAMPLE

Least prime p such that triangular(3)*p is a triangular number is p=11, so a(3) = 11.

CROSSREFS

Cf. A000217, A068084, A225502.

Sequence in context: A224418 A220947 A224417 * A012960 A013117 A120864

Adjacent sequences:  A225784 A225785 A225786 * A225788 A225789 A225790

KEYWORD

nonn

AUTHOR

Alex Ratushnyak, May 16 2013

STATUS

approved

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Last modified August 14 05:20 EDT 2022. Contains 356110 sequences. (Running on oeis4.)