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 A261621 #48 Mar 26 2017 19:21:58 %S A261621 42,73,52,101,70,149,100,229,150,379,243,159,108,251,164,421,267,174, %T A261621 449,286,823,508,1609,968,3461,2040,8111,4689,2745,1631,981,600,1987, %U A261621 1189,723,448,1423,861,530,1697,1020,3643,2146,8623,4978,22193,12602,62791 %N A261621 Rocket Sequence 42: a(0) = 42, a(n) = A073846(a(n-1)). %C A261621 This sequence has been checked up to a(108) = 106838266736 without reaching 42. It seems to be slowly climbing in value in both the negative and positive directions. Its period is either extremely large or more probably infinite. %H A261621 Chayim Lowen, <a href="/A261621/b261621.txt">Table of n, a(n) for n = 0..54</a> %F A261621 a(n+1) = A073846(a(n)). %F A261621 a(n-1) = A073898(a(n)). %e A261621 a(1) = A073846(a(0)) = A073846(42) = 73. %Y A261621 Cf. A073846, A073898, A261314, A262149. %K A261621 nonn %O A261621 0,1 %A A261621 _Chayim Lowen_, Sep 09 2015