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A165261 Long legs of primitive Pythagorean triples which have a perimeter which is the average of a twin prime pair. 2
4, 12, 77, 112, 143, 195, 209, 220, 299, 420, 425, 520, 527, 629, 700, 840, 868, 988, 1023, 1085, 1127, 1209, 1305, 1421, 1480, 1720, 1740, 1900, 2001, 2021, 2255, 2296, 2320, 2331, 2332, 2499, 2520, 2548, 2583, 2604, 2752, 2829, 2964, 3021, 3256, 3311 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..46.

EXAMPLE

see A165250.

MATHEMATICA

amax=10^5; 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; b=2*m*n; If[GCD[a, b]==1, If[a>b, {a, b}={b, a}]; If[a>amax, Break[]]; c=m^2+n^2; x=a+b+c; If[PrimeQ[x-1]&&PrimeQ[x+1], k++; AppendTo[lst, b]]]], {m, n+1, 12!, 2}], {n, 1, q, 1}]; Union@lst

CROSSREFS

Cf. A020883, A014574, A165260, A165262.

Sequence in context: A078628 A301340 A244058 * A027145 A299795 A010370

Adjacent sequences:  A165258 A165259 A165260 * A165262 A165263 A165264

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Sep 11 2009

STATUS

approved

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Last modified March 22 04:32 EDT 2019. Contains 321406 sequences. (Running on oeis4.)