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A003970
Möbius transform of A003960 (with alternating zeros omitted).
1
1, 1, 2, 3, 2, 5, 6, 2, 8, 9, 3, 11, 6, 4, 14, 15, 5, 6, 18, 6, 20, 21, 4, 23, 12, 8, 26, 10, 9, 29, 30, 6, 12, 33, 11, 35, 36, 6, 15, 39, 8, 41, 16, 14, 44, 18, 15, 18, 48, 10, 50, 51, 6, 53, 54, 18, 56, 22, 12, 24, 30, 20, 18, 63, 21, 65, 27, 8, 68, 69, 23, 30, 28, 12, 74, 75
OFFSET
1,3
LINKS
FORMULA
Multiplicative with a(p^e) = [(p-1)/2][(p+1)/2]^(e-1). - David W. Wilson, Sep 01 2001
EXAMPLE
The Möbius transform begins 1,0,1,0,2,0,3,0,2,0,5,0,6,0,2,0,8,0,9,0,3,0,11,0,...
MATHEMATICA
f[p_, e_] := ((p - 1)/2) ((p + 1)/2)^(e - 1); a[1] = 1; a[n_] := Times @@ f @@@ FactorInteger[2*n - 1]; Array[a, 100] (* Amiram Eldar, Nov 03 2023 *)
PROG
(PARI) a(n) = {my(f = factor(2*n-1)); for (i=1, #f~, p = f[i, 1]; f[i, 1] = (p-1)/2*((p+1)/2)^(f[i, 2]-1); f[i, 2] = 1); factorback(f); } \\ Michel Marcus, Feb 27 2015
CROSSREFS
Cf. A003960.
Sequence in context: A113649 A307864 A066119 * A094443 A348066 A227071
KEYWORD
nonn,easy,mult
AUTHOR
EXTENSIONS
More terms from Reiner Martin, Aug 15 2001
Further terms from David W. Wilson, Aug 29 2001
STATUS
approved