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

1,1

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.

Links

Table of n, a(n) for n=1..39.

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}]

Crossrefs

Cf. A063990.

Sequence in context: A281721 A303319 A275469 * A066539 A095390 A033384

Adjacent sequences: A178539 A178540 A178541 * A178543 A178544 A178545

Keyword

nonn

Author

Roger L. Bagula, May 29 2010

Extensions

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

Status

approved