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 A034004 #21 Jul 08 2025 20:01:12 %S A034004 0,1,3,6,1,0,1,5,2,1,2,8,3,6,4,5,5,5,6,6,7,8,9,1,1,0,5,1,2,0,1,3,6,1, %T A034004 5,3,1,7,1,1,9,0,2,1,0,2,3,1,2,5,3,2,7,6,3,0,0,3,2,5,3,5,1,3,7,8,4,0, %U A034004 6,4,3,5,4,6,5,4,9,6,5,2,8,5,6,1,5,9,5,6,3,0,6,6,6,7,0,3,7,4,1 %N A034004 Successive decimal digits of triangular numbers. %D A034004 Jason Rogers and _Jason Earls_, 0.1361015212836455566789110512013615..., A Split Novel, Lulu Press, NY, 2006, p. 84. %H A034004 Michel Marcus, <a href="/A034004/b034004.txt">Table of n, a(n) for n = 1..5355</a> %t A034004 Flatten[ IntegerDigits /@ Accumulate@ Range[0, 38]] (* _Robert G. Wilson v_, Mar 15 2012 *) %o A034004 (PARI) print1(0, ", "); for(n=1,9,d=digits(n*(n+1)/2);for(i=1,#d,print1(d[i]", "))) \\ _Charles R Greathouse IV_, Feb 07 2013 %Y A034004 Cf. A000217. %K A034004 nonn,base,easy %O A034004 1,3 %A A034004 _N. J. A. Sloane_