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 A261986 #16 Aug 12 2025 11:25:03 %S A261986 30958077,55670941,61487077,111031197,112710897,113180303,114523591, %T A261986 121275479,121963055,122830789,215074411,215182221,220162873, %U A261986 222034845,222254557,222661789,223538781,225298237,225414385,225545245,225695631,225718029,226254877,226356879 %N A261986 Numbers k such that A003313(k) = A003313(4*k). %C A261986 Terms are counterexamples to the conjecture that no shortest addition chains exist such that A003313(m)=A003313(m*2^k) for k>1, with a(1)=30958077 provided in 2008 by _Neill M. Clift_. %H A261986 Hugo Pfoertner, <a href="/A261986/b261986.txt">Table of n, a(n) for n = 1..75</a> %Y A261986 Cf. A115016, A003313 [l(k)], A086878 [l(k)=l(2*k)], A116459 [l(k)=l(3*k)], A116460 [l(k)=l(5*k)], A116461 [l(k)=l(6*k)], A116462 [l(k)=l(7*k)], A116463 [l(k)=l(9*k)], A117151 [l(k)=l(10*k)]. %K A261986 nonn %O A261986 1,1 %A A261986 _Hugo Pfoertner_, Sep 07 2015