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 A055755 4n^2+1, 2n^2+1, 2n^2-1 are all prime. 1
 3, 42, 45, 102, 132, 153, 237, 297, 375, 468, 570, 990, 2085, 2478, 2712, 3240, 4743, 5382, 5517, 6828, 7962, 8970, 8982, 9033, 9570, 9612, 9747, 9813, 10692, 12363, 12453, 12468, 12750, 13902, 14763, 14925, 15750, 16365, 17118, 17688, 19527 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS Peter J. C. Moses, Table of n, a(n) for n = 1..10000 EXAMPLE 42 is included because 4*42^2+1, 2*42^2+1, 2*42^2-1 are all prime numbers. MAPLE with(numtheory): for n from 1 to 50000 do if isprime(4*n^2+1) and isprime(2*n^2+1) and isprime(2*n^2-1) then printf(`%d, `, n) fi: od: MATHEMATICA a={}; Do[If[PrimeQ[4n^2+1] && PrimeQ[2n^2+1] && PrimeQ[2n^2-1], AppendTo[a, n]], {n, 10000}]; a (* Peter J. C. Moses, Apr 02 2013 *) CROSSREFS Cf. A001912. Sequence in context: A228456 A238717 A057013 * A249046 A237661 A116006 Adjacent sequences: A055752 A055753 A055754 * A055756 A055757 A055758 KEYWORD easy,nonn AUTHOR Harvey P. Dale, Jul 12 2000 EXTENSIONS More terms from James A. Sellers, Jul 13 2000 STATUS approved

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Last modified February 22 08:27 EST 2024. Contains 370240 sequences. (Running on oeis4.)