A345668 Last prime minus distance to last prime.

1, 2, 1, 4, 3, 6, 5, 4, 3, 10, 9, 12, 11, 10, 9, 16, 15, 18, 17, 16, 15, 22, 21, 20, 19, 18, 17, 28, 27, 30, 29, 28, 27, 26, 25, 36, 35, 34, 33, 40, 39, 42, 41, 40, 39, 46, 45, 44, 43, 42, 41, 52, 51, 50, 49, 48, 47, 58, 57, 60, 59, 58, 57, 56, 55, 66, 65, 64

Offset: 3

Author

Brian Beard, Jun 21 2021

Keywords

• nonn

Crossrefs

Cf. A049711, A151799, A175856.

Programs

Mathematica

a[n_] := 2 * NextPrime[n, -1] - n; Array[a, 100, 3] (* Amiram Eldar, Jun 21 2021 *)

Formula

a(n) = p - (n-p) = 2*p - n where p is the largest prime < n.

a(n) = A151799(n) - A049711(n).

a(n) = A175856(n-1) - 1.

Extensions

More terms from Jon E. Schoenfield, Jun 21 2021