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 A139419 #10 Jun 15 2013 23:41:25
%S A139419 1,3,9,15,22,36,48,69,87,116,141,167,194,222,269,308,368,419,471,524,
%T A139419 578,633,719,791,896,986,1077,1169,1262,1356,1451,1591,1710,1876,2020,
%U A139419 2213,2383,2604,2801,3051,3276,3502,3729,3957,4186,4416,4647,4879,5112
%N A139419 a(n) = first term of the n-th run of consecutive numbers in A136120.
%H A139419 Klaus Brockhaus, <a href="/A139419/b139419.txt">Table of n, a(n) for n=1..396</a>
%e A139419 A136120 starts 1, 3, 4, 5, 9, 10, 15, ..., so a(1) = 1, a(2) = 3, a(3) = 9.
%t A139419 f[seq_] := Module[{s = seq, n1, n2}, n++; n1 = s[[n]] + n; If[n1 <= len, n2 = Min[n - 1 + 2*s[[n]], len]; len -= n2 - n1 + 1; Drop[s, {n1, n2}], s]]; n = 0; len = 5200; First /@Split[FixedPoint[f, Range[len]], #2 - #1 == 1 &] (* _Jayanta Basu_, Jun 15 2013 - using the Mma program in A136120 *)
%Y A139419 Cf. A136120, A139418, A139420.
%K A139419 nonn
%O A139419 1,2
%A A139419 _Klaus Brockhaus_, Apr 22 2008