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

Author

Ilya Gutkovskiy, Apr 09 2020

Keywords

• nonn

Comments

Frequency of n in the array A261720 of pyramidal numbers.

Examples

			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.
		

Links

• Eric Weisstein's World of Mathematics, Pyramidal Number
• Index to sequences related to pyramidal numbers

Crossrefs

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