A083676 Triangular numbers whose sum of aliquot divisors is a prime number.

21, 55, 171, 325, 595, 741, 1081, 1711, 2485, 3081, 3655, 7021, 11325, 13861, 14365, 15931, 23005, 23653, 23871, 29403, 31375, 32131, 44551, 45451, 48205, 52003, 53301, 60031, 65341, 65703, 67161, 74691, 81003, 87571, 92665, 108811, 110215, 114481, 115921

Offset

1,1

Links

Donovan Johnson, Table of n, a(n) for n = 1..1000

Shyam Sunder Gupta, Fascinating Triangular Numbers.

Example

a(2) = 55 because sum of aliquot divisors of 55 = 1+5+11 = 17, which is a prime number.

Prog

(PARI) c=0; for(m=1, 34021, t=m*(m+1)\2; if(isprime(sigma(t)-t), c++; write("b083676.txt", c " " t))) /* Donovan Johnson, May 20 2013 */

Crossrefs

Sequence in context: A354162 A180674 A067431 * A264104 A236694 A292368

Adjacent sequences: A083673 A083674 A083675 * A083677 A083678 A083679

Keyword

nonn

Author

Shyam Sunder Gupta, Jun 15 2003

Status

approved