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 A064787 #19 Jan 25 2025 03:10:20 %S A064787 1,2,3,4,6,5,11,7,8,9,23,10,31,15,13,12,58,14,74,16,18,29,122,17,25, %T A064787 40,21,22,224,19,267,20,38,69,33,24,453,89,49,26,636,28,737,43,30,141, %U A064787 995,27,53,35,84,57,1523,34,59,36,108,257,2244,32,2528,310,41,37,77,52 %N A064787 Inverse permutation to A053212. %C A064787 a(n) is the index of A005179(n) in A007416; equivalently, a(n) is the number of minimal numbers (numbers in A007416) that are <= A005179(n). - _Jianing Song_, Aug 16 2022 %H A064787 Amiram Eldar, <a href="/A064787/b064787.txt">Table of n, a(n) for n = 1..148</a> %H A064787 <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>. %e A064787 a(23) = 122 because d(n) (A000005(n)) takes 121 different values before it first reaches 23 (at n = 2^22). %o A064787 (Haskell) %o A064787 import Data.List (elemIndex); import Data.Maybe (fromJust) %o A064787 a064787 = (+ 1) . fromJust . (`elemIndex` a053212_list) %o A064787 -- _Reinhard Zumkeller_, Apr 18 2015 %Y A064787 Cf. A053212, A005179, A007416, A000005. %K A064787 easy,nonn %O A064787 1,2 %A A064787 _N. J. A. Sloane_, Oct 20 2001 %E A064787 More terms from _Naohiro Nomoto_, Oct 31 2001 %E A064787 More terms from _David Wasserman_, Aug 14 2002