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A116902 Number of partitions of n into at least two parts such that the product of largest and smallest part exceeds n. 2
0, 0, 0, 0, 1, 2, 2, 3, 4, 6, 8, 10, 13, 16, 20, 23, 32, 36, 46, 55, 66, 78, 99, 108, 136, 160, 188, 216, 271, 296, 364, 415, 484, 559, 684, 725, 890, 1028, 1175, 1313, 1599, 1727, 2084, 2335, 2636, 3019, 3620, 3801, 4553, 5170, 5819, 6460, 7690, 8265, 9728, 10783 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

a(9)=4 since property holds for 4 partitions of 9: {7,2}, {6,3}, {5,4}, {5,2,2}.

MATHEMATICA

fun[n_]:=Select[IntegerPartitions[n], (Length[ # ]>1 && Last[ # ]First[ # ]>n)&]; Table[Length[fun[k]], {k, 40}]

(* second program: *)

f[n_] := Length@ Select[ IntegerPartitions@n, Length@# > 1 && Last@# First@# > n &]; Array[f, 56] (* Robert G. Wilson v, Apr 06 2006 *)

CROSSREFS

Cf. A000041, A116900, A116901.

Sequence in context: A114541 A077114 A118246 * A066447 A035542 A225484

Adjacent sequences:  A116899 A116900 A116901 * A116903 A116904 A116905

KEYWORD

nonn

AUTHOR

Giovanni Resta, Mar 14 2006

EXTENSIONS

More terms from Robert G. Wilson v, Apr 06 2006

STATUS

approved

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Last modified November 15 11:18 EST 2019. Contains 329144 sequences. (Running on oeis4.)