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A165237 Long legs of primitive Pythagorean triples (a,b,c) for which 2a+1, 2b+1 and 2c+1 are primes. 3
21, 56, 285, 483, 783, 999, 1269, 1593, 1911, 2613, 3003, 3596, 3621, 3740, 4136, 4233, 4928, 5096, 5451, 5828, 5840, 6320, 7040, 7280, 8036, 8468, 9021, 9296, 9591, 11660, 12075, 12573, 12705, 12920, 12956, 13563, 14396, 14595, 15429, 15561 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

See A165236.

MATHEMATICA

amax=6*10^4; lst={}; k=0; q=12!; Do[If[(e=((n+1)^2-n^2))>amax, Break[]]; Do[If[GCD[m, n]==1, a=m^2-n^2; If[PrimeQ[2*a+1], b=2*m*n; If[PrimeQ[2*b+1], If[GCD[a, b]==1, If[a>b, {a, b}={b, a}]; If[a>amax, Break[]]; c=m^2+n^2; If[PrimeQ[2*c+1], k++; AppendTo[lst, b]]]]]]; If[a>amax, Break[]], {m, n+1, 12!, 2}], {n, 1, q, 1}]; Union@lst

CROSSREFS

Cf. A020883, A165236, A156238.

Sequence in context: A031963 A067727 A254144 * A271734 A189004 A183310

Adjacent sequences:  A165234 A165235 A165236 * A165238 A165239 A165240

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Sep 09 2009

STATUS

approved

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Last modified January 24 04:35 EST 2020. Contains 331183 sequences. (Running on oeis4.)