A116656 Slowest growing sequence of semiprimes having the semiprime-pairwise-sum property: for any i<j, a(i)+a(j) is semiprime.

4, 6, 51, 115, 511, 5263, 116623, 204091, 823363, 1144363, 78325123, 883337023, 6860264683, 19613836423, 167589841663

Offset

1,1

Links

Table of n, a(n) for n=1..15.

Example

Resulting semiprimes are:
{10,55,119,515,5267,116627},
{57,121,517,5269,116629},
{166,562,5314,116674},
{626,5378,116738},
{5774,117134},
{121886}.

Mathematica

spQ[n_] := Plus @@ Last /@ FactorInteger[n] == 2; L = {0, 4}; Do[n = L[[-1]] + 1; While[! AllTrue[n + L, spQ], n++]; AppendTo[L, n], {9}]; Rest@ L (* Giovanni Resta, Jun 13 2018 *)

Crossrefs

Cf. A001358, A164979, A181620.

Sequence in context: A330978 A183369 A241159 * A012933 A013164 A013024

Adjacent sequences: A116653 A116654 A116655 * A116657 A116658 A116659

Keyword

more,nonn

Author

Zak Seidov, Feb 21 2006

Extensions

Three more terms from R. J. Mathar, Jan 23 2008

a(11)-a(12) from Donovan Johnson, Nov 11 2008

a(13) from Donovan Johnson, Jul 22 2011

a(14) from Giovanni Resta, Jun 13 2018

a(15) from Giovanni Resta, Jun 14 2018

Status

approved