A177433 List of 4-tuples of twin primes q, p, p+2 and q+2 such that 3*q < 2*p < 2*(p+2) < 3*(q+2).

3, 5, 7, 5, 11, 17, 19, 13, 71, 107, 109, 73, 179, 269, 271, 181, 347, 521, 523, 349, 1427, 2141, 2143, 1429, 2111, 3167, 3169, 2113, 3767, 5651, 5653, 3769, 5879, 8819, 8821, 5881, 10091, 15137, 15139, 10093, 10427, 15641, 15643, 10429, 11351, 17027, 17029

Offset: 1

Author

Juri-Stepan Gerasimov, May 08 2010

Keywords

• nonn
• tabf

Examples

			a(1)=3, a(2)=5, a(3)=7 and a(4)=5 because 3*3 < 2*5 < 2*(5+2) < 3*(3+2), i.e., 9 < 10 < 14 < 15.
		

Crossrefs

Cf. A176821, A177335.

Programs

Maple

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:
isA001359 := proc(n) isprime(n) and isprime(n+2) ; end proc:
for n from 1 to 400 do q := A001359(n) ; for twop from 3*q+1 to 3*q+2 by 2 do p := twop/2 ; if isA001359(p) and twop+2 < 3*q+6 then printf("%d,%d,%d,%d,",q,p,p+2,q+2) ; end if; end do: end do: # R. J. Mathar, May 10 2010

Extensions

More terms from R. J. Mathar and D. S. McNeil, May 10 2010