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A167428 Smallest non-isolated (or twin) prime > n-th non-isolated nonprime. 1
3, 3, 11, 11, 11, 17, 17, 17, 29, 29, 29, 29, 29, 29, 29, 29, 41, 41, 41, 41, 41, 41, 41, 41, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 59, 71, 71, 71, 71, 71, 71, 71, 71, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101, 101 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..64.

EXAMPLE

a(1)=3 (>0); a(2)=3 (>1); a(3)=11 (>8); a(4)=11 (>8); a(5)=11 (>10); a(6)=17 (>14).

MAPLE

A164276 := proc(n) option remember; if n = 1 then 0; else for a from procname(n-1)+1 do if isA164276(a) then return a; end if; end do; end if: end proc:

isA164276 := proc(n) not isprime(n) and ( not isprime(n+1) or not isprime(n-1) ) ; end proc:

isA001097 := proc(n) isprime(n) and ( isprime(n+2) or isprime(n-2) ); end proc:

A167428 := proc(n) for a from A164276(n)+1 do if isA001097(a) then return a; end if; end do: end proc:

seq(A167428(n), n=1..120) ; # R. J. Mathar, May 30 2010

CROSSREFS

Cf. A001097, A164276.

Sequence in context: A122167 A095019 A321082 * A318961 A309798 A068594

Adjacent sequences:  A167425 A167426 A167427 * A167429 A167430 A167431

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Nov 03 2009

EXTENSIONS

Entries checked by R. J. Mathar, May 30 2010

STATUS

approved

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Last modified September 22 22:24 EDT 2020. Contains 337291 sequences. (Running on oeis4.)