The OEIS is supported by the many generous donors to the OEIS Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A070757 Number of ways to write 4n as a sum of 4 primes. 1
 0, 1, 2, 3, 6, 7, 11, 13, 15, 21, 24, 26, 34, 38, 41, 50, 56, 57, 70, 77, 81, 96, 100, 109, 126, 129, 138, 156, 163, 175, 199, 198, 211, 239, 241, 258, 283, 281, 308, 335, 335, 360, 382, 385, 421, 445, 437, 482, 508, 503, 556, 571, 561, 632, 657, 645, 705, 726 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS Robert Israel, Table of n, a(n) for n = 1..10000 FORMULA a(n) = A259194(4*n). - Robert Israel, Oct 29 2019 EXAMPLE 4*3 = 12 = 2+2+3+5 = 3+3+3+3 hence a(3)=2. MAPLE N:= 400: # to get a(0) to a(N/4) Primes:= select(isprime, [\$1..N]): np:= nops(Primes): for j from 0 to np do g[0, j]:= 1 od: for n from 1 to 4 do g[n, 0]:= 0: for j from 1 to np do g[n, j]:= convert(series(add(g[k, j-1] *x^((n-k)*Primes[j]), k=0..n), x, N+1), polynom) od od: seq(coeff(g[4, np], x, 4*i), i=1..N/4); # Robert Israel, Oct 29 2019 PROG (PARI) a(n)={my(s=0); forprime(i=2, n, forprime(j=i, (4*n-i)\3, forprime(k=j, (4*n-i-j)\2, if(isprime(4*n-i-j-k), s++)))); s} \\ Andrew Howroyd, Oct 29 2019 CROSSREFS Cf. A259194. Sequence in context: A366641 A113545 A056825 * A056956 A171033 A269983 Adjacent sequences: A070754 A070755 A070756 * A070758 A070759 A070760 KEYWORD nonn,look AUTHOR Benoit Cloitre, May 14 2002 EXTENSIONS Corrected by Robert Israel, Oct 29 2019 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recents
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified April 20 16:19 EDT 2024. Contains 371844 sequences. (Running on oeis4.)