A109288 - OEIS

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A109288

Semiprimes equal to p*q + 1, where p and q are distinct primes.

15, 22, 34, 35, 39, 58, 86, 87, 94, 95, 119, 123, 134, 142, 143, 146, 159, 178, 202, 203, 206, 214, 215, 218, 219, 254, 299, 302, 303, 327, 335, 382, 394, 395, 446, 447, 454, 482, 502, 515, 527, 538, 543, 554, 566, 623, 634, 635, 695, 698, 699, 707, 718, 746

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,1

LINKS

Table of n, a(n) for n=1..54.

MATHEMATICA

With[{nn=60}, Take[Select[Union[Times@@#+1&/@Subsets[Prime[Range[2nn]], {2}]], PrimeOmega[#]==2&], nn]] (* Harvey P. Dale, Apr 28 2018 *)

PROG

(PARI) for(i=1, 1000, if(bigomega(i)==2&&bigomega(i+1)==2&&issquare(i)==0, print1(i+1, ", "))) (Klasen)

CROSSREFS

Cf. A109287, A109289, A109290.

Sequence in context: A038753 A006615 A114867 * A018889 A186525 A236107