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A167397
n-th single (or isolated or non-twin) prime minus n.
1
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
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
CROSSREFS
Sequence in context: A146902 A146910 A328862 * A135595 A082483 A075735
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