A333915 Number of ways to represent n as a pyramidal number.

1, 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 2, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 2, 1, 1, 1, 3, 1, 1, 1, 2, 2, 1, 1, 2, 1, 2, 1, 2, 1, 2, 1, 2, 1, 1, 1, 3, 2, 1, 1, 2, 2, 1, 1, 2, 1, 2

Offset

4,7

Comments

Frequency of n in the array A261720 of pyramidal numbers.

Links

Table of n, a(n) for n=4..100.

Eric Weisstein's World of Mathematics, Pyramidal Number

Index to sequences related to pyramidal numbers

Example

a(10) = 2 because 10 is the third tetrahedral (or triangular pyramidal) number and also the second 9-gonal pyramidal number.
a(30) = 3 because 30 is the fourth square pyramidal number, the third octagonal pyramidal number and also the second 29-gonal pyramidal number.

Crossrefs

Cf. A080851, A129654, A177025, A261720, A333916.

Sequence in context: A118663 A205119 A355150 * A293234 A347441 A360617

Adjacent sequences: A333912 A333913 A333914 * A333916 A333917 A333918

Keyword

nonn

Author

Ilya Gutkovskiy, Apr 09 2020

Status

approved