A246755 Numbers of the form 2k - 1 such that A246702(k) = 3.

15, 33, 43, 45, 69, 75, 87, 99, 109, 135, 141, 157, 159, 177, 207, 213, 225, 229, 249, 261, 277, 283, 297, 303, 307, 321, 363, 375, 393, 405, 423, 447, 477, 499, 501, 519, 531, 537, 573, 591, 621, 639, 643, 675, 681, 691, 717, 733, 739, 747, 783, 789, 807, 811

Offset: 1

Author

Juri-Stepan Gerasimov, Nov 15 2014

Keywords

• nonn

Comments

Composites in this sequence: 15, 33, 45, 69, 75, 87, 99, 135, 141, 159, 177, 207, 213, 225, 249, 261, 297, 303, 321, 363, 375, 393, 405, 423, 447, 477, ...

Examples

			A246702(8) = 3 for the first time, hence a(1) = 2*8 - 1 = 15.
		

Crossrefs

Cf. Numbers of the form 2k - 1 such that A246702(k) = m: number 1 (m = 0), A167791 (m = 1), A246717 (m = 2), this sequence (m = 3), A001133 (primes in this sequence).

Programs

PARI

is(k) = (m=Mod(k%2, k*k)) && sum(i=1, k*k-1, m*=2; m==1) == 3; \\ Jinyuan Wang, May 15 2020

Extensions

More terms from and terms corrected by Jinyuan Wang, May 15 2020