A128194 Absolute value of second differences of A005849.

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

Offset

1,1

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.

Links

Table of n, a(n) for n=1..14.

Formula

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

Example

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.

Sequence in context: A108008 A275773 A060363 * A184091 A309487 A206016

Adjacent sequences: A128191 A128192 A128193 * A128195 A128196 A128197

Keyword

nonn,more

Author

Enoch Haga, Feb 18 2007

Extensions

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

Status

approved