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Smallest sets of 3 consecutive abundant numbers in arithmetic progression. The initial abundant number is listed.
7

%I #8 Nov 11 2013 17:22:38

%S 24,42,80,100,104,114,120,126,144,162,180,196,200,220,228,234,240,246,

%T 272,282,288,304,324,348,350,364,392,402,420,426,440,460,504,572,582,

%U 588,594,608,616,624,640,654,660,666,684,700,708,714,728,736,740,786

%N Smallest sets of 3 consecutive abundant numbers in arithmetic progression. The initial abundant number is listed.

%H Shyam Sunder Gupta, <a href="/A228844/b228844.txt">Table of n, a(n) for n = 1..5000</a>

%e 24, 30, 36 is the smallest set of 3 consecutive abundant numbers in arithmetic progression so 24 is in the list.

%t AbundantQ[n_] := DivisorSigma[1, n] > 2 n; m = 2; z1 = 18; cd = 6; a = {}; Do[If[AbundantQ[n], If[n - z1 == cd, m = m + 1; If[m > 2, AppendTo[a, n - 2*cd]], m = 2; cd = n - z1]; z1 = n], {n, 19, 1000000}]; a

%Y Cf. A005101, A228433.

%K nonn

%O 1,1

%A _Shyam Sunder Gupta_, Nov 10 2013