A178542 Difference A063990(2n)-A063990(2n-1) between amicable numbers.

64, 26, 304, 544, 136, 112, 2310, 1120, 3908, 103, 1530, 3666, 1097, 21780, 784, 15660, 646, 15554, 4416, 4512, 11356, 988, 28080, 36858, 24840, 30810, 17888, 17150, 11680, 3510, 9536, 11440, 9328, 1724, 5184, 13888, 13140, 61110, 18504

Offset: 1

Author

Roger L. Bagula, May 29 2010

Keywords

• nonn

Comments

Note that these are not differences between two members of amicable pairs

(see A066539) because A063990 is sorted and may separate pairs of amicable numbers.

Crossrefs

Cf. A063990.

Programs

Mathematica

(*A063990 Amicable numbers.*);
s[n_] := DivisorSigma[1, n] - n;
AmicableNumberQ[n_] := If[Nest[s, n, 2] == n && ! s[n] == n, True, False];
a = Select[Range[10^6], AmicableNumberQ[ # ] &];
Table[a[[n + 1]] - a[[n]], {n, 1, Length[a], 2}]

Extensions

Formula clarified by the Assoc. Eds. of the OEIS - Jun 07 2010