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 A176704 Number of twin primes between non-twin prime(n) and non-twin prime(n+1). 1
 7, 2, 2, 0, 2, 2, 0, 0, 0, 4, 0, 0, 4, 0, 0, 0, 6, 0, 2, 2, 0, 0, 2, 2, 0, 2, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 2, 0, 0, 2, 0, 2, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 6, 0, 2, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 4, 0, 2, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE a(1)=7 because are 7 twin primes (3,5,7,11,13,17,19) between non-twin prime(1)=2 and non-twin prime(2)=23. MAPLE From R. J. Mathar, Apr 27 2010: (Start) isA001097 := proc(n) isprime(n) and ( isprime(n+2) or isprime(n-2) ); end proc: A001097 := proc(n) option remember; if n =1 then 3; else for a from procname(n-1)+2 by 2 do if isA001097(a) then return a; end if; end do: end if; end proc: 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: A176704 := proc(n) local a, p ; a := 0 ; for p from A007510(n)+1 to A007510(n+1)-1 do if isA001097(p) then a := a+1 ; end if; end do: return a; end proc: seq(A176704(n), n=1..120) ; (End) CROSSREFS Cf. A001097, A007510. Sequence in context: A108433 A274570 A334056 * A289917 A198415 A195723 Adjacent sequences:  A176701 A176702 A176703 * A176705 A176706 A176707 KEYWORD nonn AUTHOR Juri-Stepan Gerasimov, Apr 24 2010 EXTENSIONS Corrected (a(21)=4 removed) by R. J. Mathar, Apr 27 2010 STATUS approved

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Last modified April 23 09:42 EDT 2021. Contains 343204 sequences. (Running on oeis4.)