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%I #3 Dec 05 2013 19:56:17
%S 4,12,60,180,1620,9720,417960,7523280,308454480,25293267360,
%T 1593475843680,74893364652960,4793175337789440,517662936481259520,
%U 21224180395731640320,4075042635980474941440,611256395397071241216000
%N a(1) = 4, for n > 1, a(n) = smallest multiple of a(n-1) such that a(n)-1 and a(n)+1 are twin primes.
%t a[1] = 4; a[n_] := a[n] = Block[{k = 2}, While[ !PrimeQ[ k*a[n - 1] - 1] || !PrimeQ[ k*a[n - 1] + 1], k++ ]; k*a[n - 1]]; Table[ a[n], {n, 1, 17}]
%K nonn
%O 1,1
%A _Amarnath Murthy_, Jun 09 2003
%E Edited and extended by _Robert G. Wilson v_, Jun 15 2003