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First of 7 consecutive deficient numbers in arithmetic progression.
2

%I #7 Nov 13 2013 17:01:24

%S 801339,962649,7353339,21964299,41642139,48049689,55455939,89034939,

%T 89851449,92253849,105259539,107948379,109455339,114295449,116754939,

%U 122349369,135575979,156009849,159521049,173645439,188586699,192674169,193137849,220301769,221355125

%N First of 7 consecutive deficient numbers in arithmetic progression.

%H Shyam Sunder Gupta, <a href="/A231629/b231629.txt">Table of n, a(n) for n = 1..126</a>

%e 801339, 801341, 801343, 801345, 801347, 801349, 801351 is the smallest set of 7 consecutive deficient numbers in arithmetic progression so 801339 is in the list.

%t DefQ[n_] := DivisorSigma[1, n] < 2 n; m = 2; z1 = 2; cd = 1; a = {}; Do[If[DefQ[n], If[n - z1 == cd, m = m + 1; If[m > 6, AppendTo[a, n - 6*cd]], m = 2; cd = n - z1]; z1 = n], {n, 3, 1000000000}]; a

%Y Cf. A005100, A231623, A228964, A231624, A231625, A231626, A231628.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Nov 11 2013