OFFSET
1,1
LINKS
Paolo P. Lava, Table of n, a(n) for n = 1..100
EXAMPLE
x = 15834 -> R(x) = 43851 and sigma(15834) + sigma(43851) = 40320 + 59904 = 100224 = sigma(15834 + 43851)= sigma(59685).
MAPLE
with(numtheory): P:=proc(q) local a, b, k, n;
for n from 1 to q do a:=n; b:=0;
for k from 1 to ilog10(n)+1 do b:=10*b+(a mod 10); a:=trunc(a/10);
od; if sigma(n)+sigma(b)=sigma(n+b) then print(n); fi;
od; end: P(10^6);
MATHEMATICA
Select[Range[130000], DivisorSigma[1, #]+DivisorSigma[1, IntegerReverse[#]] == DivisorSigma[1, #+IntegerReverse[#]]&] (* Requires Mathematica version 10 or later *) (* Harvey P. Dale, Jul 27 2017 *)
PROG
(PARI) isok(n) = rn = subst(Polrev(digits(n)), x, 10); sigma(n + rn) == sigma(n) + sigma(rn); \\ Michel Marcus, Aug 29 2014
CROSSREFS
KEYWORD
nonn,base,easy
AUTHOR
Paolo P. Lava, Aug 27 2014
STATUS
approved