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A048630
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n-th 4k+1 prime times n-th 4k-1 prime.
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2
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15, 91, 187, 551, 851, 1271, 2279, 2867, 4307, 5963, 6887, 7979, 9047, 11639, 14659, 18923, 20567, 24047, 27331, 31459, 32899, 40991, 44503, 47959, 54227, 59987, 62879, 67159, 73543, 82319, 85907, 95371, 107143, 109783, 123463, 134983, 142523, 147167, 155011
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OFFSET
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1,1
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COMMENTS
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LINKS
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FORMULA
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MAPLE
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P1:= select(isprime, [seq(i, i=1..1000, 4)]):
P2:= select(isprime, [seq(i, i=3..1000, 4)]):
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MATHEMATICA
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zip[f_, x_, y_, z_] := With[{m = Max[Length[x],
Length[y]]}, f[PadRight[x, m, z], PadRight[y, m, z]]];
zip[Times,
Select[Range[1, 1000, 4], PrimeQ],
Select[Range[3, 1000, 4], PrimeQ], 0] //
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PROG
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(PARI) m=35; nm=0; np=0; pm=vector(m); pp=vector(m);
forstep(k=4, oo, 4, if(nm<m&&isprime(k-1), pm[nm++]=k-1); if(np<m&&isprime(k+1), pp[np++]=k+1); if(min(nm, np)==m, break));
(Magma) m:=95; v:=[4*k-1: k in [1..m]|IsPrime(4*k-1)]; w:=[4*k+1: k in [1..m]|IsPrime(4*k+1)]; [v[k]*w[k]:k in [1..Min([#v, #w])]]; // Marius A. Burtea, Jan 21 2020
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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