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 A061515 #9 Mar 20 2022 02:19:01
%S A061515 1,4,7,10,43,76,109,4312,7645,10978,43121011,76454344,109787677,
%T A061515 431210111091010,7645434443124343,10978767776457676,
%U A061515 43121011109101010978109109,76454344431243434312101143124312,109787677764576767645434476457645,431210111091010109781091091097876771097810978
%N A061515 a(0) = 1; a(n) is obtained by incrementing each digit of a(n-1) by 3.
%C A061515 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.
%o A061515 (Python)
%o A061515 from itertools import accumulate, repeat
%o A061515 def f(n, _): return int("".join(str(int(d)+3) for d in str(n)))
%o A061515 def aupton(nn): return list(accumulate(repeat(1, nn+1), f))
%o A061515 print(aupton(19)) # _Michael S. Branicky_, Mar 19 2022
%K A061515 base,nonn
%O A061515 0,2
%A A061515 _Amarnath Murthy_, May 08 2001
%E A061515 More terms from Larry Reeves (larryr(AT)acm.org), May 11 2001
%E A061515 a(17) corrected and a(18), a(19) by _Georg Fischer_, Mar 19 2022