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 A308375 #54 Jul 23 2019 21:10:50 %S A308375 4,6,8,9,1,3,5,6,7,9,2,3,4,6,7,8,9,10,3,5,6,7,8,9,11,12,4,6,8,9,10,12, %T A308375 13,5,6,7,9,10,11,12,13,6,8,9,10,11,12,14,15,7,9,11,12,13,14,15,8,9, %U A308375 10,12,13,14,15,16,9,10,11,12,13,14,15,17,18,1,3,5 %N A308375 Digital sum of composite numbers. %F A308375 a(n) = A007953(A002808(n)). %e A308375 The 6th term is 3 because the digital sum of 12 (the 6th composite number) is 3 (1+2). %t A308375 Total /@ IntegerDigits /@ Select[Range[104], CompositeQ] (* _Giovanni Resta_, May 28 2019 *) %o A308375 (PARI) lista(nn) = forcomposite(n=1, nn, print1(sumdigits(n), ", ")); \\ _Michel Marcus_, May 28 2019 %Y A308375 Cf. A002808 (composite numbers), A007953 (sum of digits). %Y A308375 Cf. A007605 (sum of digits of primes). %K A308375 nonn,easy,base %O A308375 1,1 %A A308375 _Kei Ryan_, May 27 2019