

A275487


Number of weird numbers (A006037) less than 2^n.


1



0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 2, 2, 3, 6, 25, 66, 134, 266, 505, 952, 1850, 3515, 6643, 12920, 26893, 55786, 114992, 234719, 473299, 946406, 1884728, 3754316, 7467998, 14845968
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OFFSET

0,11


COMMENTS

It is known that the density of weird numbers is positive, but smaller than 0.0101. The three smallest weird numbers are 70, 836 and 4030, therefore a(n) = 0 for n < 7; a(n) = 1 for 7 <= n < 10, and a(n) = 2 for 10 <= n < 12.


LINKS

Table of n, a(n) for n=0..33.


PROG

(PARI) print1(s=0); for(k=0, 30, print1(", "s+=sum(n=1<<k, 2<<k, is_A006037(2*n))))


CROSSREFS

Cf. A006037.
Sequence in context: A192366 A318039 A060631 * A096100 A260161 A195694
Adjacent sequences: A275484 A275485 A275486 * A275488 A275489 A275490


KEYWORD

nonn


AUTHOR

M. F. Hasler, Jul 30 2016


EXTENSIONS

a(25)a(33) from Amiram Eldar, Mar 17 2019


STATUS

approved



