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A303754 a(1) = 1 and for n > 1, a(n) = number of values of k, 2 <= k <= n, with A303753(k) = A303753(n), where A303753 is ordinal transform of cototient, A051953. 3
1, 1, 1, 2, 1, 3, 1, 2, 4, 5, 1, 6, 1, 3, 7, 2, 1, 8, 1, 4, 9, 3, 1, 10, 11, 12, 5, 6, 1, 13, 1, 4, 14, 15, 16, 17, 1, 18, 19, 7, 1, 20, 1, 5, 21, 2, 1, 22, 8, 9, 23, 24, 1, 25, 10, 11, 12, 6, 1, 26, 1, 7, 27, 3, 28, 29, 1, 13, 30, 14, 1, 31, 1, 32, 33, 34, 15, 35, 1, 16, 17, 36, 1, 37, 8, 18, 38, 9, 1, 39, 19, 4, 40, 2, 41, 42, 1, 43, 44, 20, 1, 45, 1, 21 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,4
COMMENTS
Ordinal transform of f, where f(1) = 0 and f(n) = A303753(n) for n > 1.
LINKS
MATHEMATICA
b[_] = 0;
A303753[n_] := A303753[n] = With[{t = EulerPhi[n] - n}, b[t] = b[t]+1];
f[n_] := If[n == 1, 0, A303753[n]];
Clear[b]; b[_] = 0;
a[n_] := a[n] = With[{t = f[n]}, b[t] = b[t]+1];
Array[a, 105] (* Jean-François Alcover, Dec 19 2021 *)
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; };
A051953(n) = (n - eulerphi(n));
v303753 = ordinal_transform(vector(up_to, n, A051953(n)));
Aux303754(n) = if(1==n, 0, v303753[n]);
v303754 = ordinal_transform(vector(up_to, n, Aux303754(n)));
A303754(n) = v303754[n];
CROSSREFS
Cf. also A081373, A303757.
Sequence in context: A331296 A270656 A045898 * A257918 A257912 A036262
KEYWORD
nonn
AUTHOR
Antti Karttunen, Apr 30 2018
STATUS
approved

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Last modified August 22 02:48 EDT 2024. Contains 375354 sequences. (Running on oeis4.)