cp's OEIS Frontend

A231623 Smallest starting deficient number for n consecutive deficient numbers in arithmetic progression.

%I A231623 #6 Nov 13 2013 15:05:54
%S A231623 1,1,1,2987,801339,221355125,221355125
%N A231623 Smallest starting deficient number for n consecutive deficient numbers in arithmetic progression.
%C A231623 The next term is a(10) > 10^9. The common difference for first 3 terms is 1 and for next 4 terms is 2.
%e A231623 First and smallest occurrence of n, n >= 3, consecutive deficient numbers in arithmetic progression:
%e A231623 a(3) = 1: (1, 2, 3);
%e A231623 a(4) = 1: (1, 2, 3, 4);
%e A231623 a(5) = 1: (1, 2, 3, 4, 5);
%e A231623 a(6) = 2987: (2987, 2989, 2991, 2993, 2995, 2997);
%e A231623 a(7) = 801339: (801339, 801341, 801343, 801345, 801347, 801349, 801351);
%e A231623 a(8) = 221355125: (221355125, 221355127, 221355129, 221355131, 221355133, 221355135, 221355137, 221355139);
%e A231623 a(9) = 221355125: (221355125, 221355127, 221355129, 221355131, 221355133, 221355135, 221355137, 221355139, 221355141);
%Y A231623 Cf. A005100, A228433.
%K A231623 nonn,hard,more
%O A231623 3,4
%A A231623 _Shyam Sunder Gupta_, Nov 11 2013