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 A278529 #27 Jun 02 2025 15:45:31 %S A278529 0,1,0,2,1,3,0,4,1,5,2,6,0,7,1,8,3,9,0,10,2,11,4,12,1,13,0,14,5,15,1, %T A278529 16,3,17,6,18,2,19,0,20,7,21,1,22,4,23,8,24,0,25,2,26,9,27,3,28,5,29, %U A278529 10,30,1,31,0,32,11,33,1,34,6,35,12,36,2,37,4,38,13,39,0,40,7,41,14,42,3,43,1,44,15,45,0,46,8,47,16,48,5,49,2,50,17,51,1,52 %N A278529 a(n) = one-based position in the round in which n is removed in the Flavius sieve, 0 if n is never removed (when n is one of the terms of A000960). %C A278529 a(n) = index of the column where n is located in array A278507, 0 if n does not occur there (when n is one of the terms of A000960). %H A278529 Antti Karttunen, <a href="/A278529/b278529.txt">Table of n, a(n) for n = 1..10707</a> %H A278529 <a href="/index/J#Josephus">Index entries for sequences related to the Josephus Problem</a> %F A278529 For n > 1, a(A100287(n)) = 1. %o A278529 (Scheme) %o A278529 ;; Very crude. Find it with two nested loops. (Maybe a closed form exists?) %o A278529 (define (A278529 n) (cond ((not (zero? (A278169 n))) 0) ((even? n) (/ n 2)) (else (let searchrow ((row 2)) (let searchcol ((col 1)) (cond ((>= (A278507bi row col) n) (if (= (A278507bi row col) n) col (searchrow (+ 1 row)))) (else (searchcol (+ 1 col))))))))) %o A278529 ;; Code for A278507bi given in A278507. %Y A278529 One less than A278539. %Y A278529 Cf. A278507, A278528 (the other index). %Y A278529 Cf. A000960 (positions of zeros), A100287 (positions of 1's, after the initial 1). %K A278529 nonn %O A278529 1,4 %A A278529 _Antti Karttunen_, Nov 23 2016