A152900 Primes p such that there exists a triangular number t with p*t also triangular.

2, 3, 5, 7, 11, 13, 19, 23, 29, 31, 41, 43, 53, 71, 73, 89, 109, 127, 131, 157, 163, 181, 211, 233, 239, 241, 271, 281, 307, 379, 419, 421, 431, 461, 463, 541, 599, 601, 613, 701, 743, 757, 811, 827, 929, 977, 991, 1123, 1259, 1481, 1483, 1559, 1721, 1723

Offset

1,1

Comments

Sequence A152899 contains the triangular numbers t.

Links

T. D. Noe, Table of n, a(n) for n=1..1000

Example

11 is here because 21 and 11*21 are triangular.

Mathematica

TriQ[n_]:=IntegerQ[Sqrt[1+8n]]; Select[Prime[Range[1000]], TriQ[2#-1] || TriQ[2#+1] || TriQ[(#-1)/2] || TriQ[(#+1)/2] &]

Crossrefs

A000217

Sequence in context: A007459 A129944 A176162 * A079151 A274335 A049643

Adjacent sequences: A152897 A152898 A152899 * A152901 A152902 A152903

Keyword

nonn

Author

T. D. Noe, Dec 14 2008

Status

approved