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A066925 Numbers k having a partition k = sum x_i for which sum k/x_i is the same partition of k. 5
1, 4, 9, 16, 18, 24, 25, 30, 36, 40, 48, 49, 64, 70, 72, 81, 84, 90, 96, 100, 108, 112, 120, 121, 126, 144, 150, 154, 160, 162, 168, 169, 180, 192, 196, 198, 204, 208, 210, 216, 220, 225, 228, 234, 240, 250, 252, 256, 264, 270, 276, 280, 286, 288, 289, 294 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Giovanni Resta, Table of n, a(n) for n = 1..1000

EXAMPLE

24 is in the sequence because 24 = 2+4+6+12 and 12/2 + 12/4 + 12/6 + 12/12 gives the same partition 2+4+6+12.

MATHEMATICA

SelfInvPart[n_, x_, terms_] := If[Length[terms]==0||x<0, False, If[x==0, True, If[IntegerQ[Sqrt[n]]&&SelfInvPart[n, x-Sqrt[n], terms], True, If[IntegerQ[n/First[terms]]&&SelfInvPart[n, x-First[terms]-n/First[terms], terms], True, SelfInvPart[n, x, Rest[terms]]]]]]; TestSelfInv[n_] := SelfInvPart[n, n, Divisors[n]]; Select[Range[100], TestSelfInv]

CROSSREFS

Cf. A066926.

Sequence in context: A313319 A313320 A066926 * A313321 A313322 A122379

Adjacent sequences:  A066922 A066923 A066924 * A066926 A066927 A066928

KEYWORD

nonn,nice

AUTHOR

David Eppstein, Jan 23 2002

EXTENSIONS

More terms from Dean Hickerson, Jan 27 2002

STATUS

approved

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Last modified September 25 23:09 EDT 2021. Contains 347664 sequences. (Running on oeis4.)