A368041 -id:A368041 - cp's OEIS frontend

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A368074 a(n) is the least number k such that the k-th n-gonal number can be written as the difference of two positive n-gonal numbers in exactly n ways.

Original entry on oeis.org

5, 12, 82, 105, 297, 182

Offset: 3

Ilya Gutkovskiy, Dec 10 2023

The corresponding n-gonal numbers are in A368075.

			a(3) = 5: T(5) = T(6) - T(3) = T(8) - T(6) = T(15) - T(14), where T(k) is the k-th triangular number.

Eric Weisstein's World of Mathematics, Polygonal Number

Cf. A086270, A338105, A368041, A368075.

A368075 a(n) is the least n-gonal number that can be expressed as the difference of two positive n-gonal numbers in exactly n ways.

Original entry on oeis.org

15, 144, 10045, 21945, 220077, 99008

Offset: 3

Ilya Gutkovskiy, Dec 10 2023

The corresponding indices of n-gonal numbers are in A368074.

			a(3) = 15: 15 = 21 - 6 = 36 - 21 = 120 - 105.

Eric Weisstein's World of Mathematics, Polygonal Number

Cf. A086270, A338105, A368041, A368074.

Showing 1-2 of 2 results.