

A275491


Number of primitive weird numbers (A002975) below 10^n.


4



0, 0, 1, 2, 7, 13, 24, 48, 85, 152, 277, 499, 881
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OFFSET

0,4


COMMENTS

It is not known unconditionally whether there are infinitely many primitive weird numbers (PWN; A002975), although numerical data provides strong evidence: even the number of weird numbers of the form 2^k*p*q (A258882, A258333) seems to increase rapidly as k increases. G. Melfi has shown that Cramer's conjecture implies the infiniteness of PWN.


LINKS



PROG

(PARI) s=0; vector(22, n, s+=sum(n=10^n\20+1, 10^n\2, is_A002975(n*2)))
(PARI) vector(22, n, #select(t>t<10^n, A002975)) \\ If A002975 is defined as set, vector, or list with enough terms.


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



