A274591 Least number k such that k-1, k, k+1 are the sum of two nonzero squares in exactly n ways.

73, 22049, 90707201, 4359889

Offset

1,1

Comments

Corresponding triples are (72, 73, 74), (22048, 22049, 22050), (90707200, 90707201, 90707202), (4359888, 4359889, 4359890) for first four terms.

a(6) = 1428907401, a(8) = 2305281745. No more terms < 2*10^11. - Lars Blomberg, Jun 01 2018

a(5) > 10^15, if it exists. - Giovanni Resta, Jun 05 2018

Links

Table of n, a(n) for n=1..4.

Example

a(2) = 22049 because 22048 = 12^2 + 148^2 = 68^2 + 132^2, 22049 = 32^2 + 145^2 = 40^2 + 143^2, 22050 = 21^2 + 147^2 = 105^2 + 105^2.

Crossrefs

Cf. A064716, A274548.

Sequence in context: A210382 A091757 A070531 * A232293 A351800 A364440

Adjacent sequences: A274588 A274589 A274590 * A274592 A274593 A274594

Keyword

nonn,hard,more

Author

Altug Alkan, Jun 29 2016

Status

approved