|
|
A176807
|
|
Lesser of twin primes p such that p = semiprime(k)/3 and p + 2 = semiprime(k+3)/3 for some integer k.
|
|
0
|
|
|
3, 107, 137, 179, 239, 419, 461, 659, 1049, 1091, 1697, 1787, 1871, 2027, 2111, 2381, 2687, 2711, 3167, 3299, 3329, 3359, 3371, 3467, 3851, 4259, 4721, 4967, 5279, 5501, 5639, 5651, 5867, 6269, 6449, 7487, 8819, 8969, 9011, 9431, 9629
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
EXAMPLE
|
3 is a term because 3 = semiprime(3)/3 = 9/3 and 3 + 2 = 5 = semiprime(3+3)/3 = 15/3.
|
|
MAPLE
|
isA001358 := proc(n) numtheory[bigomega](n) = 2 ; end proc:
A001358 := proc(n) option remember ; if n = 1 then 4; else for a from procname(n-1)+1 do if isA001358(a) then return a; end if; end do: end if ; end proc:
A174956 := proc(p) option remember ; for n from 1 do if A001358(n) = p then return n; elif A001358(n) > p then return 0 ; end if; end do: end proc:
A001359 := proc(n) option remember; if n = 1 then 3; else for a from procname(n-1)+2 by 2 do if isprime(a) and isprime(a+2) then return a; end if; end do: end if; end proc:
for i from 1 to 200 do p := A001359(i) ; n := A174956(3*p) ; n3 := A174956(3*p+6) ; if n > 0 and n3 >0 and n3=n+3 then printf("%d, ", p) ; end if; end do: (End)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn
|
|
AUTHOR
|
|
|
EXTENSIONS
|
Corrected (659 inserted, 1031 removed, 2027 inserted) and extended by R. J. Mathar, Apr 27 2010
|
|
STATUS
|
approved
|
|
|
|