

A108183


Primes equal to the sum of two successive semiprimes.


3



19, 29, 43, 47, 59, 67, 73, 127, 151, 167, 173, 233, 283, 313, 317, 461, 521, 541, 593, 653, 701, 719, 727, 787, 839, 907, 967, 1249, 1409, 1439, 1471, 1549, 1601, 1831, 1867, 1873, 1913, 1993, 2029, 2083, 2089, 2287, 2311, 2351, 2393, 2579, 2593, 2693
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OFFSET

1,1


COMMENTS

Primes p such that p = sum of nth and (n+1)st semiprimes for some n.


LINKS



EXAMPLE

19 = sp(3) + sp(4) = 9 + 10 where sp(n) = nth semiprime.
29 is a member because 2*7 + 3*5 = 29.
13 is not a member because although 2*2 + 3*3 = 13, 4 and 9 are not successive semiprimes.


MATHEMATICA

Select[ Plus @@@ Partition[ Select[ Range[1250], Plus @@ Last /@ FactorInteger[ # ] == 2 &], 2, 1], PrimeQ[ # ] &] (* Robert G. Wilson v, Jun 14 2005 *)
Select[Total/@Partition[Select[Range[1500], PrimeOmega[#]==2&], 2, 1], PrimeQ] (* Harvey P. Dale, Nov 15 2013 *)


CROSSREFS



KEYWORD

easy,nonn


AUTHOR



EXTENSIONS



STATUS

approved



