A232892 Numbers whose sum of proper square divisors is a palindrome in base 10 having at least two digits.

144, 324, 1089, 1936, 5929, 13225, 30752, 46128, 58564, 76880, 92256, 107632, 125316, 138384, 149769, 153760, 154449, 169136, 199888, 215264, 230640, 261392, 292144, 322896, 338272, 342225, 353648, 378225, 399776, 405769, 445904, 461280, 476656, 507408, 522784, 538160, 568912

Offset

1,1

Links

Table of n, a(n) for n=1..37.

Example

Sum of proper square divisors of 324: 81+36+9+4+1=131, is a palindrome with three digits.

Mathematica

pb10Q[n_]:=Module[{t=Total[Select[Most[Divisors[n]], IntegerQ[ Sqrt[ #]]&]]}, IntegerLength[ t]>1&&PalindromeQ[t]]; Select[Range[ 600000], pb10Q] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jun 01 2017 *)

Prog

(PARI)
reverse(n)=concat(Vecrev(Str(n)))
palind(n)=(Str(n)==reverse(n)&&n>10)
{for(n=1, 6*10^5, k=sumdiv(n, d, d*issquare(d)*(d<n)); if(palind(k), print(n)))}

Crossrefs

Cf. A232893.

Sequence in context: A217584 A030633 A189988 * A034285 A211469 A248551

Adjacent sequences: A232889 A232890 A232891 * A232893 A232894 A232895

Keyword

nonn,base

Author

Antonio Roldán, Dec 02 2013

Status

approved