A072363 Composite numbers whose sum of divisors is palindromic.

4, 81, 96, 98, 130, 146, 162, 166, 201, 205, 208, 221, 244, 274, 300, 314, 325, 333, 365, 388, 422, 438, 489, 519, 559, 633, 685, 793, 803, 1376, 1419, 1505, 1548, 1806, 1841, 2021, 2268, 2284, 2305, 2561, 2611, 2666, 2751, 2763, 2838, 2881, 2892, 2967, 3010

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..10000

Example

a(2) = 81: sum of divisors of 81 = 1+3+9+27+81 = 121, which is a palindrome.

Mathematica

Select[Range[3000], CompositeQ[#] && PalindromeQ @ DivisorSigma[1, #] &] (* Amiram Eldar, Aug 17 2020 *)

Crossrefs

Cf. A000203, A002113, A072362.

Sequence in context: A159063 A337053 A258981 * A272884 A053901 A017006

Adjacent sequences: A072360 A072361 A072362 * A072364 A072365 A072366

Keyword

base,nonn

Author

Shyam Sunder Gupta, Jul 18 2002

Extensions

More terms from Amiram Eldar, Aug 17 2020

Status

approved