1,2

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

Eric Weisstein's World of Mathematics, Heptagonal Number

Index to sequences related to polygonal numbers

Let S(k, m) denote the sum of m heptagonal numbers starting from the k-th. We have

a(1) = S(1, 1);

a(2) = S(13, 2) = S(3, 8);

a(3) = S(133, 98) = S(479, 14) = S(168, 77);

a(4) = S(6773, 1785) = S(810, 6006) = S(7467, 1547) = S(38758, 70).

Cf. A000566, A054859, A068314, A186337, A298467, A322636, A334007, A334008, A334010, A334012.

Sequence in context: A214285 A251841 A251085 * A206312 A252211 A045258

Adjacent sequences: A334008 A334009 A334010 * A334012 A334013 A334014

nonn,hard,more

Ilya Gutkovskiy, Apr 12 2020

a(4) from Giovanni Resta, Apr 14 2020

approved