A128279 an=n-th smallest integer of the form m=p1*p2 where pi are odd primes such that d+2m/d are all primes for d dividing 2m.

15, 21, 35, 39, 51, 65, 95, 155, 221, 329, 371, 485, 519, 611, 905, 989, 1121, 1199, 1469, 1509, 1541, 1661, 1821, 3039, 3189, 3431, 3641, 3791, 4055, 4109, 4281, 4601, 4859, 5079, 5111, 5195, 5331, 5429, 5579, 5951, 5979, 6161, 6245, 6731, 6881, 7415

Offset

1,1

Links

Table of n, a(n) for n=1..46.

Example

E.g. 35=5.7, 2.5.7+1=71, 2.5+7=17, 2.7+5=19. 5.7+2=37 are all primes and this is the 3rd such number, so a(3)=35

Crossrefs

Cf. A128276, A128277, A128278, A045536.

Sequence in context: A296244 A309005 A225916 * A099611 A081934 A095147

Adjacent sequences: A128276 A128277 A128278 * A128280 A128281 A128282

Keyword

nonn

Author

Kok Seng Chua (chuakokseng(AT)hotmail.com), Mar 05 2007

Status

approved