This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A163125 #14 Sep 04 2022 17:00:37
%S A163125 1,3,5,7,9,2,4,6,8,10,12,14,16,9,2,4,6,8,10,12,14,16,18,11,4,6,8,10,
%T A163125 12,14,16,18,20,4,6,8,10,12,14,16,18,20,4,6,8,10,12,14,16,18,20,13,6,
%U A163125 8,10,12,14,16,18,20,13,15,8,10,12,14,16,18,20,13,15,17,10,12,14,16,18,20,13
%N A163125 Sum of digits of the n-th Self-number (or Colombian number), A003052(n).
%H A163125 Amiram Eldar, <a href="/A163125/b163125.txt">Table of n, a(n) for n = 1..10000</a>
%F A163125 a(n) = A007953(A003052(n)).
%e A163125 a(6) = 2 + 0 = 2;
%e A163125 a(7) = 3 + 1 = 4.
%p A163125 A007953 := proc(n) add( d,d= convert(n,base,10) ); end:
%p A163125 isA003052 := proc(n) local k ; for k from 0 to n do if k+A007953(k) = n then RETURN(false): fi; od: RETURN(true) ; end:
%p A163125 A003052 := proc(n) option remember; if n = 1 then 1; else for a from procname(n-1)+1 do if isA003052(a) then RETURN(a) ; fi; od; fi; end:
%p A163125 A163125 := proc(n) A007953( A003052(n)) ; end: seq(A163125(n),n=1..100) ; # _R. J. Mathar_, Jul 27 2009
%t A163125 sumdig[n_] := Plus @@ IntegerDigits[n]; m = 500; sumdig /@ Complement[Range[m], Table[n + sumdig[n], {n, 1, m}]] (* _Amiram Eldar_, Nov 28 2020 *)
%Y A163125 Cf. A003052, A007953.
%K A163125 nonn,base
%O A163125 1,2
%A A163125 _Juri-Stepan Gerasimov_, Jul 21 2009
%E A163125 Values after a(51) corrected by _R. J. Mathar_, Jul 27 2009