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A197881
Number of times n occurs in A197863.
1
1, 0, 0, 2, 0, 0, 0, 1, 2, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 4, 0, 0, 0, 0, 0, 0, 0, 2
OFFSET
1,4
FORMULA
Multiplicative with a(p^e) = 0 if e = 1, 2 if e = 2, and 1 otherwise.
MATHEMATICA
f[p_, e_] := Switch[e, 1, 0, 2, 2, _, 1]; a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[n]; Array[a, 100] (* Amiram Eldar, Aug 28 2023 *)
PROG
(PARI) a(n)=my(es=factor(n)[, 2]~); prod(k=1, #es, if(es[k]==1, 0, if(es[k]==2, 2, 1)))
(Scheme) (define (A197881 n) (cond ((= 1 n) n) (else (* (case (A067029 n) ((1) 0) ((2) 2) (else 1)) (A197881 (A028234 n)))))) ;; Antti Karttunen, Jul 23 2017
CROSSREFS
Sequence in context: A025086 A035699 A132406 * A332712 A079126 A339086
KEYWORD
nonn,easy,mult
AUTHOR
EXTENSIONS
More terms from Antti Karttunen, Jul 23 2017
STATUS
approved