A080851 -id:A080851 - cp's OEIS frontend

A359321 a(n) is the smallest n-gonal pyramidal number which can be represented as the sum of n distinct nonzero n-gonal pyramidal numbers in exactly n ways, or -1 if none exists.

2300, 6201, 8125, 6391

Offset: 3

Ilya Gutkovskiy, Dec 25 2022

			For n = 3: 2300 = 1 + 969 + 1330 = 56 + 220 + 2024 = 165 + 364 + 1771.
For n = 4: 6201 = 1 + 91 + 1785 + 4324 = 1 + 285 + 1015 + 4900 = 30 + 140 + 506 + 5525 = 91 + 819 + 1496 + 3795.

Eric Weisstein's World of Mathematics, Pyramidal Number

Cf. A080851, A350210, A350397, A350423.

A360836 a(n) is the least n-gonal pyramidal number that is the sum of two or more consecutive nonzero n-gonal pyramidal numbers in more than one way.

Original entry on oeis.org

12880, 18896570

Offset: 2

Ilya Gutkovskiy, Feb 23 2023

a(4) > 10^19 if it exists. - Michael S. Branicky, Feb 23 2023

			For n = 2: 12880 = 91 + ... + 903 = 300 + ... + 990.
For n = 3: 18896570 = 708561 + ... + 1021384 = 2604125 + ... + 2796160.

Eric Weisstein's World of Mathematics, Pyramidal Number

Cf. A080851, A360762.

cp's OEIS Frontend

A359321 a(n) is the smallest n-gonal pyramidal number which can be represented as the sum of n distinct nonzero n-gonal pyramidal numbers in exactly n ways, or -1 if none exists.

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A360836 a(n) is the least n-gonal pyramidal number that is the sum of two or more consecutive nonzero n-gonal pyramidal numbers in more than one way.

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