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 A061516 #9 Aug 09 2025 07:36:38
%S A061516 1,5,9,13,57,911,1355,5799,9111313,13555757,5799911911,
%T A061516 911131313551355,1355575757995799,579991191191113139111313,
%U A061516 9111313135513551355575713555757,135557575799579957999119115799911911
%N A061516 a(0) = 1; a(n) is obtained by incrementing each digit of a(n-1) by 4.
%C A061516 In A061511-A061522, A061746-A061750 when the incremented digit exceeds 9 it is written as a 2-digit string. So 9+1 becomes the 2-digit string 10, etc.
%t A061516 a[0]=1;a[n_]:=a[n]=FromDigits[Flatten[IntegerDigits/@(IntegerDigits[a[n-1]]+4)]]; Table[a[n],{n,0,15}] (* _Zak Seidov_, Mar 09 2006 *)
%K A061516 base,nonn
%O A061516 0,2
%A A061516 _Amarnath Murthy_, May 08 2001
%E A061516 More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001