OFFSET
1,2
COMMENTS
LINKS
Chai Wah Wu, Table of n, a(n) for n = 1..10000
Eric Weisstein's World of Mathematics, Palindromic Number
Eric Weisstein's World of Mathematics, Divisor Function
Eric Weisstein's World of Mathematics, Digit Sum
EXAMPLE
a(3) = 11, 11 is the palindromic number, digitsum(11) = 1 + 1 = 2, sigma_0(11) = 2.
MATHEMATICA
fQ[n_] := Block[{d = IntegerDigits@ n}, And[d == Reverse@ d, Total@ d == DivisorSigma[0, n]]]; Select[Range[2^19], fQ] (* Michael De Vlieger, Oct 27 2015 *)
Select[Range[600000], PalindromeQ[#]&&Total[IntegerDigits[#]] == DivisorSigma[ 0, #]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Aug 28 2019 *)
PROG
(PARI) lista(nn) = {for(n=1, nn, my(d = digits(n)); if ((Vecrev(d) == d) && (numdiv(n) == sumdigits(n)), print1(n, ", ")); ); } \\ Michel Marcus, Oct 25 2015
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Ilya Gutkovskiy, Oct 24 2015
STATUS
approved