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A169605 Numbers x of the form x=2*y-3=3*z-2 where y and z are primes. 1
7, 19, 31, 55, 91, 139, 175, 199, 211, 379, 391, 451, 499, 535, 631, 715, 919, 931, 1039, 1135, 1291, 1315, 1399, 1435, 1639, 1711, 1759, 1819, 1855, 1891, 1939, 2179, 2215, 2359, 2431, 2515, 2575, 2719, 2731, 2899, 2971, 3115, 3271, 3691, 3775, 3955, 4195 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..47.

EXAMPLE

a(1)=7 because 5*2-3=3*3-2, a(2)=19 because 11*2-3=7*3-2.

MAPLE

isA169605 := proc(x) if type(x+3, 'even') then if (x+2) mod 3 = 0 then isprime( (x+3)/2) and isprime((x+2)/3) ; else false ; end if else false; end if; end proc: for x from 1 to 10000 do if isA169605(x) then printf("%d, ", x) ; end if; end do: # R. J. Mathar, Jan 27 2010

MATHEMATICA

Select[3Prime[Range[250]]-2, PrimeQ[(3+#)/2]&] (* Harvey P. Dale, May 11 2011 *)

PROG

(Sage) # code from D. S. McNeil:

is_prime_Q = lambda x: x.is_integral() and Integer(x).is_prime()

A169605 = list(x for x in range(1, 10**4) if is_prime_Q((x+3)/2) and

is_prime_Q((x+2)/3))

A169605[:36]

CROSSREFS

Cf. A000040, A131426.

Sequence in context: A216530 A114564 A191118 * A216532 A249375 A212492

Adjacent sequences:  A169602 A169603 A169604 * A169606 A169607 A169608

KEYWORD

nonn

AUTHOR

Juri-Stepan Gerasimov, Dec 03 2009

EXTENSIONS

Corrected and extended by Jim Nastos and D. S. McNeil, Dec 21 2009

A few more terms from R. J. Mathar, Jan 27 2010

STATUS

approved

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Last modified October 23 20:19 EDT 2017. Contains 293813 sequences.