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a(n) = (p+2)!/p! where p is the n-th lesser twin prime, A001359(n).
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%I #11 Apr 29 2023 08:10:03

%S 20,42,156,342,930,1806,3660,5256,10506,11772,19182,22650,32580,37056,

%T 39402,52212,57840,73170,79806,97656,121452,176820,187056,213906,

%U 273006,325470,360600,382542,412806,436260,656910,676506,686412,737022,778806

%N a(n) = (p+2)!/p! where p is the n-th lesser twin prime, A001359(n).

%H Harvey P. Dale, <a href="/A126251/b126251.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = 2*A082669(n).

%p ZL:=[]:for p from 1 to 1653 do if (isprime(p) and isprime(p+2)) then ZL:=[op(ZL),((p+2)!/p!)]; fi; od; print(ZL);

%t #[[2]]!/#[[1]]!&/@Select[Partition[Prime[Range[200]],2,1],#[[2]]-#[[1]] == 2&] (* _Harvey P. Dale_, Feb 16 2020 *)

%Y Cf. A001359, A082669.

%Y Subsequence of A002378.

%K easy,nonn

%O 1,1

%A _Zerinvary Lajos_, Mar 08 2007

%E Name edited by _Michel Marcus_, Apr 29 2023