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

1,2

Comments

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

Links

Table of n, a(n) for n=1..31.

Formula

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

Example

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

Crossrefs

Cf. A061712.

Sequence in context: A337384 A063600 A116926 * A242832 A114634 A088017

Adjacent sequences: A140327 A140328 A140329 * A140331 A140332 A140333

Keyword

easy,base,nonn

Author

Jonathan Vos Post, May 26 2008

Extensions

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

Status

approved