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%I #13 Aug 08 2015 22:28:22
%S 1,2,1,3,4,5,6,7,720,11,12,13,3360,17,18,19,9240,23,11793600,29,30,31,
%T 45239040,37,59280,41,42,43,91080,47,311875200,53,549853920,59,60,61,
%U 1072431360,67,328440,71,72,73,2533330800,79,531360,83,4701090240,89
%N a(1) = 1, then product of consecutive composite numbers sandwiched between primes.
%C a(1) = a(3) = 1 as empty product is defined to be 1.
%C The odd numbered terms are in A061214. - _T. D. Noe_, Oct 02 2012
%F a(2n) = prime(n) and a(2n+1)= product of composite numbers between prime(n) and prime(n+1).
%F a(2n) = A000040(n). a(2n+1) = A072472(n)/A000040(n+1). - _R. J. Mathar_, May 02 2007
%p A109919 := proc(n) local p; if n mod 2 = 0 then ithprime(n/2) ; elif n = 1 then 1 ; else p := ithprime((n-1)/2) ; mul(i,i=p+1..nextprime(p)-1) ; fi ; end: for n from 1 to 80 do printf("%d, ",A109919(n)) ; od ; # _R. J. Mathar_, May 02 2007
%Y Cf. A109920.
%Y Cf. A072472.
%Y Cf. A061214 (product of composite numbers between primes).
%K easy,nonn
%O 1,2
%A _Amarnath Murthy_, Jul 16 2005
%E More terms from _R. J. Mathar_, May 02 2007
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