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A126251
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a(n)=(p+2)!/p! if p prime and p+2 prime.
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2
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20, 42, 156, 342, 930, 1806, 3660, 5256, 10506, 11772, 19182, 22650, 32580, 37056, 39402, 52212, 57840, 73170, 79806, 97656, 121452, 176820, 187056, 213906, 273006, 325470, 360600, 382542, 412806, 436260, 656910, 676506, 686412, 737022, 778806
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OFFSET
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1,1
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COMMENTS
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a(n)=2*A082669
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LINKS
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Harvey P. Dale, Table of n, a(n) for n = 1..1000
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MAPLE
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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);
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MATHEMATICA
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#[[2]]!/#[[1]]!&/@Select[Partition[Prime[Range[200]], 2, 1], #[[2]]-#[[1]] == 2&] (* Harvey P. Dale, Feb 16 2020 *)
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CROSSREFS
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Cf. A082669.
Sequence in context: A256102 A128672 A290184 * A100515 A220006 A295795
Adjacent sequences: A126248 A126249 A126250 * A126252 A126253 A126254
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KEYWORD
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easy,nonn
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AUTHOR
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Zerinvary Lajos, Mar 08 2007
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STATUS
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approved
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