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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 Antti Karttunen, Table of n, a(n) for n = 1..65537 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. A051953, A303753. Cf. also A081373, A303757. Sequence in context: A331296 A270656 A045898 * A257918 A257912 A036262 Adjacent sequences: A303751 A303752 A303753 * A303755 A303756 A303757 KEYWORD nonn AUTHOR Antti Karttunen, Apr 30 2018 STATUS approved

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Last modified June 5 22:25 EDT 2023. Contains 363138 sequences. (Running on oeis4.)