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 A071635 Number of decompositions of 4*n+2 into sum of two primes of form 4*k+1. 3
 0, 0, 1, 0, 1, 1, 1, 1, 2, 0, 2, 2, 1, 2, 3, 0, 3, 2, 2, 3, 2, 1, 3, 2, 1, 4, 3, 2, 5, 3, 2, 5, 3, 2, 3, 4, 2, 5, 4, 1, 5, 3, 3, 4, 4, 1, 6, 4, 3, 6, 5, 2, 9, 3, 3, 4, 4, 2, 6, 4, 2, 8, 4, 4, 5, 4, 3, 8, 5, 2, 7, 7, 4, 9, 6, 3, 7, 6, 3, 6, 6, 2, 12, 5, 4, 8, 6, 5, 10, 4, 2, 10, 7, 4 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,9 LINKS Andrew Howroyd, Table of n, a(n) for n = 0..10000 FORMULA a(n) = A002375(2*n+1) - A156642(n). - Vladimir Shevelev, Feb 12 2009 EXAMPLE a(10)=2 as 4*10+2=42=5+37=(4*1+1)+(4*9+1)=13+29=(4*3+1)+(4*7+1) and the other two decompositions 42=11+31=(4*2+3)+(4*7+3)=19+23=(4*4+3)+(4*5+3), A002375(21)=4; for a(m)=0 see A071636. PROG (PARI) a(n)={my(s=0); forprime(p=3, 2*n+1, if(p%4==1 && isprime(4*n+2-p), s++)); s} \\ Andrew Howroyd, Feb 02 2020 CROSSREFS Cf. A002375, A002144, A156642. Sequence in context: A060964 A118206 A029314 * A156643 A308626 A268755 Adjacent sequences:  A071632 A071633 A071634 * A071636 A071637 A071638 KEYWORD nonn,look AUTHOR Reinhard Zumkeller, May 27 2002 STATUS approved

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Last modified December 4 15:46 EST 2020. Contains 338928 sequences. (Running on oeis4.)