OFFSET
1,1
COMMENTS
The sum of the aliquot divisors of n must be greater than one. - Harvey P. Dale, Aug 12 2012
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
a(8) = 21: sum of aliquot divisors of 21 = 1+3+7 = 11, which is a palindrome.
MATHEMATICA
adpQ[n_]:=Module[{sad=Total[Most[Divisors[n]]], idsad}, idsad = IntegerDigits[sad]; sad>1&&idsad==Reverse[idsad]]; Select[Range[ 700], adpQ] (* Harvey P. Dale, Aug 12 2012 *)
Select[Range[1000], CompositeQ[#] && PalindromeQ @ (DivisorSigma[1, #] - #) &] (* Amiram Eldar, Aug 17 2020 *)
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Shyam Sunder Gupta, Jul 18 2002
STATUS
approved