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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, 29628007, 59231668, 118528637 (list; graph; refs; listen; history; text; internal format)
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
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
KEYWORD
nonn,more
AUTHOR
M. F. Hasler, Jul 30 2016
EXTENSIONS
a(25)-a(33) from Amiram Eldar, Mar 17 2019
a(34)-a(36) from Amiram Eldar, May 26 2023
STATUS
approved

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Last modified May 25 11:12 EDT 2024. Contains 372788 sequences. (Running on oeis4.)