A154332 Least positive integer m such that A087285(n) = A154333(m) = m^3 - next smaller square.

3, 2, 32, 15, 17, 4, 7, 6, 35, 8, 11, 10, 14, 21, 12, 28, 65, 9, 56, 18, 136, 568, 23, 99, 101, 20, 13, 27, 34, 30, 143, 145, 38, 16, 19, 47, 195, 91, 197, 175, 26, 51, 59, 799, 69, 62, 163, 255, 257, 66, 31, 717, 2904, 33, 377, 79, 323, 325, 25

Offset: 1

Author

M. F. Hasler, Jan 07 2009

Keywords

• nonn

Comments

The terms of this sequence constitute a "proof" for the terms listed in A087285. To prove that a number is NOT in A087285, one can check the finite number (A081120) of solutions to the corresponding Mordell equation, cf. references in A081121.

Programs

PARI

A154332(n) = { local(m); until(m++^3-sqrtint(m^3-1)^2==A087285[n],); m }

Formula

A087285(n) = A154333(a(n)) = a(n)^3 - [sqrt(a(n)^3 - 1)]^2 = A000578(a(n)) - A048760(a(n)^3-1).