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A071700
Product of twin primes of form (4*k+3,4*(k+1)+1), k>=0.
8
15, 143, 3599, 5183, 11663, 32399, 36863, 51983, 57599, 97343, 121103, 176399, 186623, 359999, 435599, 685583, 1040399, 1065023, 1192463, 1327103, 1742399, 2039183, 2108303, 2214143, 2585663, 2624399, 2782223
OFFSET
1,1
LINKS
FORMULA
a(n) >> n^2 log^4 n. - Charles R Greathouse IV, Jul 03 2013
PROG
(PARI) for(k=0, 1e3, if(isprime(4*k+3)&&isprime(4*k+5), print1(16*k^2+32*k +15", "))) \\ Charles R Greathouse IV, Jul 03 2013
(PARI) is(n)=my(k=sqrtint(n\16)); n==16*k^2+32*k+15 && isprime(4*k+3) && isprime(4*k+5) \\ Charles R Greathouse IV, Jul 03 2013
(PARI) is(n)=my(t); n%16==15 && issquare(n+1, &t) && isprime(t-1) && isprime(t+1) \\ Charles R Greathouse IV, Dec 12 2016
(PARI) list(lim)=my(v=List(), p=3); forprime(q=5, sqrtint(1+lim\1)+1, if(q-p==2 && p%4==3, listput(v, p*q)); p=q); Vec(v) \\ Charles R Greathouse IV, Dec 12 2016
(Haskell)
a071700 n = a071700_list !! (n-1)
a071700_list = [x * y | x <- [3, 7 ..], a010051' x == 1,
let y = x + 2, a010051' y == 1]
-- Reinhard Zumkeller, Aug 05 2014
CROSSREFS
Subsequence of A037074, A071700 and of A182140.
Cf. A071697, a(n) = A071698(n)*A071699(n).
Sequence in context: A177065 A173406 A291619 * A133126 A240158 A255944
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Jun 04 2002
STATUS
approved