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A231624
Smallest sets of 3 consecutive deficient numbers in arithmetic progression. The initial deficient number is listed.
6
1, 2, 3, 7, 8, 9, 13, 14, 15, 17, 21, 25, 27, 31, 32, 33, 37, 39, 43, 44, 45, 49, 50, 51, 53, 57, 61, 62, 63, 67, 69, 73, 74, 75, 77, 81, 85, 87, 91, 92, 93, 97, 99, 101, 105, 109, 111, 115, 116, 117, 121, 122, 123, 127, 128, 129, 133, 134, 135, 137, 141
OFFSET
1,2
LINKS
EXAMPLE
1, 2, 3 is the smallest set of 3 consecutive deficient numbers in arithmetic progression so 1 is in the list.
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 > 2, AppendTo[a, n - 2*cd]], m = 2; cd = n - z1]; z1 = n], {n, 3, 1000000}]; a
CROSSREFS
KEYWORD
nonn
AUTHOR
Shyam Sunder Gupta, Nov 11 2013
STATUS
approved