A128194 Absolute value of second differences of A005849.

4432, 3490, 266, 11069, 1911, 13619, 27010, 3982, 140425, 72738, 21768, 752305, 4100791, 4622387

Offset: 1

Author

Enoch Haga, Feb 18 2007

Keywords

• nonn
• more

Comments

In this sequence a(4) and a(6) are primes. Also a(2)+1, a(7)+1 and a(8)+1 are primes. And a(11)-1 is prime. These may at some future time begin three new sequences.

Examples

			a(1) = 4432 because the first two values of first differences in A128193 are 140 and 4572. 4572-140 = 4432, the first second difference.
		

Crossrefs

Cf. A005849 A128193.

Formula

a(n) = abs(A128193(n+1) - A128193(n)). - Amiram Eldar, Jul 17 2025

Extensions

Offset changed to 1, a(9)-a(10) corrected and a(13)-a(14) added by Amiram Eldar, Jul 17 2025