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A095686
Half the number of divisors of nonsquares (A000037).
2
1, 1, 1, 2, 1, 2, 2, 1, 3, 1, 2, 2, 1, 3, 1, 3, 2, 2, 1, 4, 2, 2, 3, 1, 4, 1, 3, 2, 2, 2, 1, 2, 2, 4, 1, 4, 1, 3, 3, 2, 1, 5, 3, 2, 3, 1, 4, 2, 4, 2, 2, 1, 6, 1, 2, 3, 2, 4, 1, 3, 2, 4, 1, 6, 1, 2, 3, 3, 2, 4, 1, 5, 2, 1, 6, 2, 2, 2, 4, 1, 6, 2, 3, 2, 2, 2, 6, 1, 3, 3, 1, 4, 1, 4, 4, 2, 1, 6, 1, 4, 2, 5, 1, 4, 2
OFFSET
1,4
COMMENTS
The first occurrence of n in the sequence corresponds to the nonsquare = A003680(n) = A005179(2n).
Also number of unordered divisor pairs (d,n/d) for n=A000037. - Lekraj Beedassy, Jul 30 2004
LINKS
FORMULA
a(n)=A000005(A000037(n))/2.
MATHEMATICA
m=11; DivisorSigma[0, Complement[Range[m^2], Range[m]^2]]/2 (* Amiram Eldar, Nov 05 2019 *)
PROG
(PARI) lista(nn) = {for (i = 1, nn, if (! issquare(i), print1(numdiv(i)/2, ", ")); ); } \\ Michel Marcus, Jul 27 2013
CROSSREFS
Sequence in context: A224362 A350560 A050362 * A105258 A329173 A366493
KEYWORD
nonn
AUTHOR
Lekraj Beedassy, Jul 05 2004
EXTENSIONS
Corrected and extended by Ray Chandler, Jul 09 2004
STATUS
approved