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A303758
a(1) = 1 and for n > 1, a(n) = number of values of k, 2 <= k <= n, with A002322(k) = A002322(n), where A002322 is Carmichael lambda.
3
1, 1, 1, 2, 1, 3, 1, 4, 2, 2, 1, 5, 1, 3, 3, 4, 1, 4, 1, 5, 5, 2, 1, 6, 1, 2, 2, 6, 1, 6, 1, 1, 3, 2, 3, 7, 1, 3, 4, 7, 1, 8, 1, 4, 5, 2, 1, 8, 2, 2, 3, 6, 1, 4, 3, 9, 5, 2, 1, 9, 1, 2, 10, 4, 7, 5, 1, 5, 3, 8, 1, 11, 1, 2, 4, 6, 3, 9, 1, 10, 1, 2, 1, 12, 6, 3, 3, 6, 1, 10, 11, 4, 4, 2, 3, 2, 1, 4, 5, 5, 1, 7, 1, 12, 13
OFFSET
1,4
COMMENTS
Ordinal transform of f, where f(1) = 0 and f(n) = A002322(n) for n > 1.
LINKS
FORMULA
Except for a(2) = 1, a(n) = A303756(n).
MATHEMATICA
a[1] = 1; a[n_] := With[{c = CarmichaelLambda[n]}, Select[Range[2, n], c == CarmichaelLambda[#]&] // Length];
Array[a, 1000] (* Jean-François Alcover, Sep 19 2020 *)
PROG
(PARI)
up_to = 65537;
ordinal_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), pt); for(i=1, length(invec), if(mapisdefined(om, invec[i]), pt = mapget(om, invec[i]), pt = 0); outvec[i] = (1+pt); mapput(om, invec[i], (1+pt))); outvec; };
A002322(n) = lcm(znstar(n)[2]); \\ From A002322
Aux303758(n) = if(1==n, 0, A002322(n));
v303758 = ordinal_transform(vector(up_to, n, Aux303758(n)));
A303758(n) = v303758[n];
CROSSREFS
Cf. A002322.
Cf. also A303756, A303757.
Sequence in context: A238800 A375266 A067734 * A161904 A360678 A346697
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 30 2018
STATUS
approved