A261080 Semiprimes p*q for which p and q are successive primes and their binary representations differ from each other in one bit position only.

6, 35, 323, 437, 899, 1763, 2021, 4757, 9797, 10403, 19043, 22499, 27221, 38021, 39203, 72899, 79523, 95477, 99221, 131753, 145157, 154433, 164009, 205193, 210677, 213443, 250997, 272483, 324899, 381923, 412163, 416021, 455621, 549077, 557993, 594437, 656099, 675683, 736163, 741317, 777923, 783221, 826277, 870473, 881717, 974153, 1022117, 1102499, 1127843, 1238753

Offset: 1

Author

Antti Karttunen, Sep 23 2015

Keywords

• nonn

Comments

Numbers n for which A260737(n) = A261079(n) = 1.

Examples

			6 is included as 6 = 2*3, 2 and 3 are successive primes, and 2 (in binary "10") and 3 (in binary "11") differ by only one bit from each other.
		

Links

• Harvey P. Dale, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A205302, A205511, A260737, A261079.

Intersection of A006094 and A261077.

Programs

Mathematica

brdQ[{a_,b_}]:=Module[{c=IntegerDigits[a,2],d=IntegerDigits[b,2]}, Length[ c] == Length[d]&&Count[Total/@Transpose[{c,d}],1]==1]; Times@@@ Select[ Partition[Prime[Range[200]],2,1],brdQ] (* Harvey P. Dale, Jan 29 2016 *)

Formula

a(n) = A205511(n) * A205302(n).