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 A053241 #13 Oct 27 2023 22:00:45 %S A053241 1,2,3,4,6,7,8,9,10,11,12,13,14,15,16,17,18,19,22,23,24,25,26,27,28, %T A053241 30,31,32,33,35,36,37,38,39,40,41,42,43,44,45,46,47,48,51,52,53,54,55, %U A053241 58,59,60,61,62,63,64,66,67,68,69,71,72,73,74,75,76,77,78,81,82,83,84,85 %N A053241 Numbers n such that A053238(n) = 2. %H A053241 Reinhard Zumkeller, <a href="/A053241/b053241.txt">Table of n, a(n) for n = 1..10000</a> %p A053241 with(numtheory): f := [seq( `if`((sigma(i) > sigma(i+1)),i,print( )), i=1..5000)]; %p A053241 seq( `if`(f[i+1] - f[i] = 2,i,print( )), i=1..100); %o A053241 (Haskell) %o A053241 import Data.List (elemIndices) %o A053241 a053241 n = a053241_list !! (n-1) %o A053241 a053241_list = map (+ 1) $ elemIndices 2 a053238_list %o A053241 -- _Reinhard Zumkeller_, Oct 16 2011 %Y A053241 Cf. A000203, A053226, A053238, A053239, A053240 (complement), A053242, A053243, A053244, A053245. %K A053241 nonn %O A053241 1,2 %A A053241 _Asher Auel_, Jan 10 2000