A305887 - OEIS

A305887

The least increasing sequence of numbers where all pairwise sums are semiprimes, with a(1)=4.

4, 5, 10, 29, 173, 249, 19073, 71489, 1166789, 3800333, 7021253, 15920129, 84551600693

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OFFSET

1,1

COMMENTS

All terms > 10 are congruent to {3, 9} mod 10.

Triangle of resulting semiprimes begins:

14, 15

33, 34, 39

177, 178, 183, 202

LINKS

MATHEMATICA

Nest[Append[#, Block[{k = Last[#] + 1}, While[! AllTrue[#, PrimeOmega[k + #] == 2 &], k++]; k]] &, {4}, 7] (* Michael De Vlieger, Jun 14 2018 *)

CROSSREFS

KEYWORD

nonn,more

AUTHOR

Zak Seidov, Jun 14 2018

EXTENSIONS

a(13) from Giovanni Resta, Jun 14 2018

STATUS

approved