A368041 a(n) is the least number k such that k^2 can be written as the difference of two positive squares in exactly n ways.

1, 3, 8, 16, 12, 64, 128, 24, 512, 1024, 48, 4096, 72, 60, 32768, 65536, 192, 144, 524288, 384, 2097152, 4194304, 120, 16777216, 432, 1536, 134217728, 576, 3072, 1073741824, 2147483648, 240, 1152, 17179869184, 12288, 68719476736, 137438953472, 360, 1728, 1099511627776

Offset: 0

Author

Ilya Gutkovskiy, Dec 09 2023

Keywords

• nonn

Comments

Index of first occurrence of n in A046079.

All the terms are of the form 2^m * A147516(k), m >= 0, k >= 1. - Amiram Eldar, Nov 08 2024

Examples

			a(2) = 8: 8^2 = 10^2 - 6^2 = 17^2 - 15^2.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 0..999

Crossrefs

Cf. A025487, A046079, A068314, A071571, A094191, A100073, A122842, A147516.

Formula

a(n) = min(A122842(n+1), 2*A071571(n)). - Jon E. Schoenfield, Dec 09 2023

Extensions

a(26)-a(29) from Michel Marcus, Dec 09 2023

a(30)-a(39) from Jon E. Schoenfield, Dec 09 2023