|
Search: id:A113043
|
|
|
| A113043 |
|
Number of ways you can split the set of the first n primes into two proper subsets of which the sum of one is twice the sum of the other. |
|
+0
1
|
|
| 0, 0, 0, 0, 0, 0, 0, 0, 0, 11, 0, 0, 0, 0, 0, 255, 0, 766, 0, 2342, 0, 0, 0, 23373, 0, 75005, 0, 243824, 0, 800249, 0, 2643880, 0, 8789565, 0, 29396169, 0, 0, 0, 333867426, 0, 1132658742, 0, 3858864902, 0, 13182921033, 0, 0, 0, 0, 0, 537690715092, 0
(list; graph; listen)
|
|
|
OFFSET
|
1,10
|
|
|
MAPLE
|
A113043:=proc(n) local i, j, p, t; t:=0; for j from 2 to n do p:=1; for i to j do p:=p*(x^(-2*ithprime(i))+x^(ithprime(i))); od; t:=t, coeff(p, x, 0); od; t; end;
with (numtheory): sp:= proc(n) option remember; `if` (n=1, 2, sp(n-1) +ithprime(n)) end: b:= proc() option remember; local i, j, t; `if` (args[1]=0, `if` (nargs=2, 1, b(args[t] $t=2..nargs)), add (`if` (args[j] -ithprime (args[nargs]) <0, 0, b(sort ([seq (args[i] -`if` (i=j, ithprime (args[nargs]), 0), i=1..nargs-1)])[], args[nargs]-1)), j=1..nargs-1)) end: a:= proc(n) local m; m:= sp(n); `if` (irem(m, 3)=0, b(m/3, 2*m/3, n), 0) end: seq (a(n), n=1..70); [From Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 06 2009]
|
|
CROSSREFS
|
Cf. A022894.
Sequence in context: A057141 A034249 A131679 this_sequence A110408 A138066 A115595
Adjacent sequences: A113040 A113041 A113042 this_sequence A113044 A113045 A113046
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
Floor van Lamoen (fvlamoen(AT)hotmail.com), Oct 12 2005
|
|
EXTENSIONS
|
Extended beyond a(40) by Alois P. Heinz (heinz(AT)hs-heilbronn.de), Sep 06 2009
|
|
|
Search completed in 0.002 seconds
|
