1,1

The next term is too large to include.

5 = 4!! - 3!! + 2!! - 1!! -1 = 8 - 3 + 2 - 1 - 1.

P:=proc(n) local a, i, j, k, w; for i from 1 by 1 to n do a:=0; for j from i by -1 to 0 do k:=j; w:=j-2; while w>0 do k:=k*w; w:=w-2; od; a:=a+k*(-1)^j od; if isprime(abs(a)-1) then print(abs(a)-1); fi; od; end: P(1000);

Cf. A071828, A130309.

Adjacent sequences: A130305 A130306 A130307 this_sequence A130309 A130310 A130311

Sequence in context: A042763 A075983 A094161 this_sequence A053516 A085523 A152425

nonn,bref

Paolo P. Lava & Giorgio Balzarotti (ppl(AT)spl.at), May 21 2007