A050218 Sums of digits of Smith numbers A006753.

4, 4, 9, 13, 13, 13, 4, 13, 4, 13, 13, 13, 13, 13, 18, 13, 13, 15, 13, 15, 13, 13, 13, 13, 18, 21, 15, 13, 15, 15, 18, 15, 15, 18, 15, 13, 17, 18, 15, 22, 15, 15, 15, 22, 13, 15, 13, 22, 22, 15, 4, 13, 13, 13, 13, 15, 17, 18, 13, 15, 15, 13, 13, 22, 17, 18, 21, 22, 13, 15

Offset: 1

Author

Eric W. Weisstein

Keywords

• nonn
• base
• less

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• Eric Weisstein's World of Mathematics, Smith Number.
• Wikipedia, Smith number.

Crossrefs

Cf. A006753, A050219, A050220.

Cf. A202388, A050223.

Programs

Mathematica

d[n_]:=IntegerDigits[n]; tr[n_]:=Transpose[FactorInteger[n]]; t={}; Do[If[!PrimeQ[n]&&(x=Total[d[n]])==Total[d@tr[n][[1]]*tr[n][[2]],2],AppendTo[t,x]],{n,4,1850}]; t (* Jayanta Basu, Jun 04 2013 *)

Formula

a(n) = A007953(A006753(n)).

Extensions

Offset corrected by Reinhard Zumkeller, Dec 19 2011