cp's OEIS Frontend

A205001 Least k such that n divides the k-th difference between distinct triangular numbers.

%I A205001 #6 Feb 27 2013 09:44:10
%S A205001 1,1,3,6,2,8,5,28,4,11,14,8,20,7,13,120,35,12,44,11,26,18,65,34,17,25,
%T A205001 16,49,104,24,119,496,23,42,22,58,170,52,31,41,209,30,230,29,40,75,
%U A205001 275,134,39,62,50,38,350,37,74,49,61,117,434,48
%N A205001 Least k such that n divides the k-th difference between distinct triangular numbers.
%C A205001 For a guide to related sequences, see A204892.
%e A205001 The triangular numbers: s(k)=k(k+1)/2.
%e A205001 Their differences, ordered as in A193974:
%e A205001 u(1)=s(2)-s(1)=2
%e A205001 u(2)=s(3)-s(1)=5
%e A205001 u(3)=s(3)-s(2)=3
%e A205001 u(4)=s(4)-s(1)=9
%e A205001 u(5)=s(4)-s(2)=7
%e A205001 u(6)=s(4)-s(3)=4.
%e A205001 a(1)=1 because 1 divides u(1)
%e A205001 a(2)=1 because 2 divides u(1)
%e A205001 a(3)=3 because 3 divides u(3)
%e A205001 a(4)=6 because 4 divides u(6)
%e A205001 a(5)=2 because 5 divides u(2)
%e A205001 a(6)=8 because 6 divides u(8)
%t A205001 (See the program at A205002.)
%Y A205001 Cf. A205002, A204892.
%K A205001 nonn
%O A205001 1,3
%A A205001 _Clark Kimberling_, Jan 21 2012