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 A386643 #9 Aug 06 2025 17:34:43 %S A386643 1,2,3,2,3,4,5,3,7,9,5,7,4,10,6,13,16,18,5,17,10,22,22,8,17,6,21,15, %T A386643 27,18,16,18,23,7,12,35,35,36,28,13,15,37,8,21,30,16,37,26,30,41,23, %U A386643 19,9,28,33,13,28,44,50,35,60,58,53,10,47,61,41,37,26,34,70,15,66,34,50,11,55,19,70,70 %N A386643 Elimination order of the first person in a variation of the Josephus problem in which one person is skipped, then one is eliminated, then two people are skipped and one eliminated, then three people are skipped and so on. %e A386643 Consider 4 people in a circle. Initially, person number 1 is skipped, and person 2 is eliminated. The remaining people are now in order 3, 4, 1. Then, two people are skipped, and person 1 is eliminated, implying that the order of elimination of the first person is 2: a(4) = 2. %Y A386643 The first column of triangle A386639. %Y A386643 Cf. A000096, A225381, A386641. %K A386643 nonn %O A386643 1,2 %A A386643 _Tanya Khovanova_, _Nathan Sheffield_, and the MIT PRIMES STEP junior group, Jul 27 2025