A140330 Smallest nonprime with Hamming weight n (i.e., with exactly n 1's when written in binary).

1, 6, 14, 15, 55, 63, 247, 255, 511, 1023, 2047, 4095, 12287, 16383, 32767, 65535, 196607, 262143, 983039, 1048575, 2097151, 4194303, 8388607, 16777215, 33554431, 67108863, 134217727, 268435455, 536870911, 1073741823, 3221225471

Offset: 1

Author

Jonathan Vos Post, May 26 2008

Keywords

• easy
• base
• nonn

Comments

Apart from the first term, identical to A089226. - R. J. Mathar, May 31 2008

Examples

			a(10) = 1023 because 1023 base 2 = 1111111111 which has 10 1's and 1023 = 3 * 11 * 31 is nonprime.
		

Crossrefs

Cf. A061712.

Formula

a(n) = MIN{k such that k is in A018252 and A000120(k) = n}.

Extensions

More terms from R. J. Mathar, May 31 2008