OFFSET
1,1
COMMENTS
A conjecture of Goldbach type says every number >= 26 is of this form.
EXAMPLE
12=2^2*2 + 2*2
MAPLE
H := proc(n::posint) local p, q, r, s; p := 2; while p<=floor(sqrt((n-4)/2)) do q := 2; while q<=floor((n-4)/p^2) do s := 2; while s<=floor((n-p^2*q)/2) do r := (n-p^2*q)/s; if type(r, posint) then if isprime(r) then return(true, p, q, s, r); end if; end if; s := nextprime(s); end do; q := nextprime(q); end do; p := nextprime(p); end do; return(false); end:
MATHEMATICA
Take[ Union[ Flatten[ Table[ Prime[p]^2*Prime[q] + Prime[r]*Prime[s], {p, 1, 6}, {q, 1, 15}, {r, 1, 15}, {s, 1, 15}]]], 70]
CROSSREFS
KEYWORD
nonn
AUTHOR
Mario Maqueda Garcia [Garci'a] (israelmira(AT)terra.es), Mar 03 2003
EXTENSIONS
Edited and extended by Robert G. Wilson v, Mar 05 2003
STATUS
approved