A167397 n-th single (or isolated or non-twin) prime minus n.

1, 21, 34, 43, 48, 61, 72, 75, 80, 87, 102, 115, 118, 143, 148, 151, 156, 193, 204, 213, 230, 235, 240, 253, 268, 281, 290, 303, 308, 323, 328, 335, 340, 345, 348, 353, 360, 363, 370, 399, 402, 407, 414, 423, 434, 441, 444, 451, 454, 459, 490, 495, 504, 509

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..2500

Formula

a(n) = A007510(n) -A000027(n).

Example

a(1) =  2 - 1 =  1,
a(2) = 23 - 2 = 21,
a(3) = 37 - 3 = 34.

Maple

A007510 := proc(n) option remember; if n <= 2 then op(n, [2, 23]) ; else for a from procname(n-1)+2 by 2 do if isprime(a) and not isprime(a+2) and not isprime(a-2) then return a; end if; end do: end if; end proc:
A167397 := proc(n) A007510(n)-n ; end proc:
seq(A167397(n), n=1..120) ; # R. J. Mathar, May 30 2010

Mathematica

Module[{nn=150, ntp}, ntp=Select[Prime[Range[nn]], NoneTrue[#+{2, -2}, PrimeQ]&]; #[[1]]-#[[2]]&/@Thread[{ntp, Range[Length[ntp]]}]] (* Harvey P. Dale, Nov 24 2024 *)

Crossrefs

Cf. A000027, A007510.

Sequence in context: A146902 A146910 A328862 * A135595 A082483 A075735

Adjacent sequences: A167394 A167395 A167396 * A167398 A167399 A167400

Keyword

nonn

Author

Juri-Stepan Gerasimov, Nov 02 2009, Nov 05 2009

Extensions

Corrected (220 replaced with 230, 225 with 235) by R. J. Mathar, May 30 2010

Status

approved