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 A110742 #11 Sep 25 2023 07:23:25 %S A110742 0,2,1,8,27,0,211,500,0,5404,23137,0,269736,806856,0,10508986, %T A110742 43103947,0 %N A110742 Number of primes with digit sum n having at most n digits. %C A110742 a(3n) = 0 for n > 1. %C A110742 The binary version of this sequence is the characteristic function of A000043. [_David Wasserman_, Dec 17 2008] %e A110742 For a(2) the two primes are 2 and 11. 101 is not included because it has 3 digits. %o A110742 (PARI) f(n, i, left, num) = if (i == n - 1, return(left <= 9 && isprime(num + left*10^i))); sum(j = 0, min(left, 9), f(n, i + 1, left - j, num + j*10^i)); %o A110742 a(n) = f(n, 0, n, 0); \\ _David Wasserman_, Dec 17 2008 %Y A110742 Cf. A110741. %K A110742 base,nonn,more %O A110742 1,2 %A A110742 _Amarnath Murthy_, Aug 10 2005 %E A110742 a(7)-a(10) from _Donovan Johnson_, Mar 23 2008 %E A110742 More terms from _David Wasserman_, Dec 17 2008