A115454 Composite positive integers written in base 2.

100, 110, 1000, 1001, 1010, 1100, 1110, 1111, 10000, 10010, 10100, 10101, 10110, 11000, 11001, 11010, 11011, 11100, 11110, 100000, 100001, 100010, 100011, 100100, 100110, 100111, 101000, 101010, 101100, 101101, 101110, 110000, 110001

Offset: 1

Author

Leroy Quet, Jan 22 2006

Keywords

• base
• nonn

Comments

If n is in the sequence then so is 10 * n. - David A. Corneth, Aug 17 2018

Links

• Robert Israel, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A002808, A007088, A004676.

Programs

Maple

map(convert,remove(isprime, [$4..200]),binary); # Robert Israel, Aug 17 2018

Mathematica

For[n = 2, n < 50, n++, If[Not[PrimeQ[n]], Print[BaseForm[n, 2]]]] (* Stefan Steinerberger, Jan 24 2006 *)

PARI

lista(nn) = forcomposite(n=1, nn, print1(fromdigits(binary(n), 10), ", ")); \\ Michel Marcus, Aug 17 2018

Formula

a(n) = A007088(A002808(n)).

Extensions

More terms from Stefan Steinerberger, Jan 24 2006