A007992 Augmented amicable pairs (smaller member of each pair).

6160, 12220, 23500, 68908, 249424, 425500, 434784, 649990, 660825, 1017856, 1077336, 1238380, 1252216, 1568260, 1754536, 2166136, 2362360, 2482536, 2537220, 2876445, 3957525, 4177524, 4287825, 5224660, 5559510, 5641552

Offset

1,1

Comments

Let f(n) = 1 + sum of aliquot divisors of n; these are pairs (n,m) with f(n)=m, f(m)=n.

m cannot equal n. - Harvey P. Dale, May 18 2012

The term "augmented amicable numbers" was coined by Beck and Wajar (1977), who found the first 11 pairs. They also found the next 25 pairs (1993). - Amiram Eldar, Mar 09 2024

Links

Amiram Eldar, Table of n, a(n) for n = 1..1159

Walter E. Beck and Rudolph M. Wajar, More reduced amicable pairs, Fibonacci Quarterly, Vol. 15, No. 4 (1977), pp. 331-332.

Walter E. Beck and Rudolph M. Wajar, Reduced and Augmented Amicable Pairs to 10^8, Fibonacci Quarterly, Vol. 31, No. 4 (1993), pp. 295-298.

David Moews, Augmented amicable pairs.

J. O. M. Pedersen, Tables of Aliquot Cycles.

J. O. M. Pedersen, Tables of Aliquot Cycles. [Cached copy, pdf file only]

Paul Pollack, Quasi-Amicable Numbers are Rare, J. Int. Seq. 14 (2011), Article 11.5.2.

Eric Weisstein's World of Mathematics, Augmented Amicable Pair.

Mathematica

aapQ[n_]:=Module[{c=DivisorSigma[1, n]+1-n}, c!=n&&DivisorSigma[ 1, c]+1-c == n]; Transpose[Union[Sort[{#, DivisorSigma[1, #]+1-#}]&/@Select[Range[ 6000000], aapQ]]] [[1]] (* Harvey P. Dale, May 18 2012 *)

Crossrefs

Cf. A015630.

Sequence in context: A204626 A318251 A281265 * A033288 A266586 A057880

Adjacent sequences: A007989 A007990 A007991 * A007993 A007994 A007995

Keyword

nonn,nice

Author

N. J. A. Sloane

Status

approved