A334008 a(n) is the least integer that can be expressed as the sum of one or more consecutive nonzero pentagonal numbers in exactly n ways.

1, 287, 472320, 89051435880

Offset

1,2

Links

Table of n, a(n) for n=1..4.

Eric Weisstein's World of Mathematics, Pentagonal Number

Index to sequences related to polygonal numbers

Example

Let S(k, m) denote the sum of m pentagonal numbers starting from the k-th. We have
a(1) = S(1, 1);
a(2) = S(14, 1) = S(2, 7);
a(3) = S(103, 24) = S(19, 80) = S(67, 41);
a(4) = S(10833, 484) = S(4542, 1936) = S(9153, 660) = S(2817, 3036);

Crossrefs

Cf. A000326, A054859, A068314, A186337, A298467, A319184, A334007, A334010, A334011, A334012.

Sequence in context: A112245 A289339 A011817 * A035882 A244512 A214301

Adjacent sequences: A334005 A334006 A334007 * A334009 A334010 A334011

Keyword

nonn,hard,more

Author

Ilya Gutkovskiy, Apr 12 2020

Extensions

a(4) from Giovanni Resta, Apr 13 2020

Status

approved