cp's OEIS Frontend

A093313 Number of permutations s_1,s_2,...,s_n of 1,2,...,n with s_1 = 2 and such that for all j=1,2,...,n, s_j divides Sum_{i=1..j} s_i.

%I A093313 #8 Feb 05 2019 18:45:12
%S A093313 0,1,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,
%T A093313 0,6,6,1,11,9,15,14,14,23
%N A093313 Number of permutations s_1,s_2,...,s_n of 1,2,...,n with s_1 = 2 and such that for all j=1,2,...,n, s_j divides Sum_{i=1..j} s_i.
%C A093313 An easy calculation turns out that the beginning elements are always: 2,1,3,6,(then either 4 or 12),...
%C A093313 The total number of permutations with this property is given in A067957.
%H A093313 Matthijs Coster, <a href="http://www.coster.demon.nl/sequences.htm">Sequences</a>
%H A093313 Matthijs Coster, <a href="http://www.nieuwarchief.nl/serie5/pdf/naw5-2002-03-1-092.pdf">Problem 2001/3-A of the Universitaire Wiskunde Competitie</a>, Nieuw Arch. Wisk. 5/3 (2002), 92-94.
%e A093313 There is a unique permutation of the numbers 1..38, starting with 2, namely:
%e A093313 2 1 3 6 12 24 8 28 21 35 14 22 4 20 25 5 23 11 33 27 9 37 10 19 7 29 15 30 16 31 17 32 36 34 38 18 26 13
%e A093313 with corresponding sums
%e A093313 2 3 6 12 24 48 56 84 105 140 154 176 180 200 225 230 253 264 297 324 333 370 380 399 406 435 450 480 496 527 544 576 612 646 684 702 728 741.
%Y A093313 Cf. A067957, A093314, A093315.
%K A093313 nonn,more
%O A093313 1,36
%A A093313 _Matthijs Coster_, Apr 26 2004; revised Aug 05 2005