A231630 Smallest sets of 8 consecutive deficient numbers in arithmetic progression. The initial deficient number is listed.
221355125, 221355127, 402640539, 402640541, 668862579, 668862581, 739577139, 739577141
Offset: 1
Keywords
Examples
221355125, 221355127, 221355129, 221355131, 221355133, 221355135, 221355137, 221355139 is the smallest set of 8 consecutive deficient numbers in arithmetic progression so 221355125 is in the list.
Programs
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Mathematica
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 > 7, AppendTo[a, n - 7*cd]], m = 2; cd = n - z1]; z1 = n], {n, 3, 1000000000}]; a