A216670 Tribonacci numbers which can be written in the form a^2 + b^2.

0, 1, 2, 4, 13, 81, 149, 274, 3136, 10609, 35890, 755476, 1389537, 4700770, 1132436852, 80641778674, 10562230626642, 15832480722303616, 333269972246340068, 19341322569415713958901, 120346786571258131649185, 15762679542071167858843489

Offset

1,3

Comments

Tribonacci numbers A000073 that are the sum of 2 nonnegative squares.

Links

Table of n, a(n) for n=1..22.

Formula

A000073 INTERSECTION A001481.

Example

a(4) = 4 = 2^2 + 0^2.
a(8) = 274 = 7^2 + 15^2.
a(11) = 35890 = 13^2 + 189^2 = 49^2 + 183^2 = 103^2 + 159^2 = 117^2 + 149^2.

Crossrefs

Cf. A000073, A001481.

Sequence in context: A298065 A298714 A306445 * A103845 A055463 A369313

Adjacent sequences: A216667 A216668 A216669 * A216671 A216672 A216673

Keyword

nonn

Author

Jonathan Vos Post, Sep 13 2012

Status

approved