A325901 Numbers having at least two representations as multinomial coefficients M(n;lambda), where lambda is a partition of n into distinct parts.

1, 10, 15, 21, 28, 35, 36, 45, 55, 56, 60, 66, 78, 84, 91, 105, 120, 126, 136, 153, 165, 168, 171, 190, 210, 220, 231, 252, 253, 276, 280, 286, 300, 325, 330, 351, 360, 364, 378, 406, 435, 455, 462, 465, 495, 496, 504, 528, 560, 561, 595, 630, 660, 666, 680

Offset

1,2

Comments

Numbers that are repeated in the triangle A309992 (all positive integers except 2 occur at least once).

All triangular numbers (A000217) except 0, 3 and 6 are in this sequence.

All terms are also contained in A325472.

Links

Alois P. Heinz, Table of n, a(n) for n = 1..10000

Wikipedia, Multinomial coefficients

Wikipedia, Partition (number theory)

Example

1 is in the sequence because M(0;0) = M(1;1) = M(2;2) = M(3;3) = ... = 1.
10 is in the sequence because M(10;9,1) = M(5;3,2) = 10.
55 is in the sequence because M(55;54,1) = M(11;9,2) = 55.
105 is in the sequence because M(7;4,2,1) = M(15;13,2) = M(105;104,1) = 105.

Crossrefs

Cf. A000009, A000217, A309992, A325472, A325903.

Sequence in context: A336548 A115708 A068992 * A098564 A168103 A322045

Adjacent sequences: A325898 A325899 A325900 * A325902 A325903 A325904

Keyword

nonn

Author

Alois P. Heinz, Sep 07 2019

Status

approved