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 A330746 Number of values of k, 1 <= k <= n, with A017666(k) = A017666(n), where A017666(n) = n/gcd(n, sigma(n)). 3
 1, 1, 1, 1, 1, 2, 1, 1, 1, 2, 1, 2, 1, 2, 3, 1, 1, 1, 1, 1, 1, 2, 1, 2, 1, 2, 1, 3, 1, 4, 1, 1, 3, 2, 1, 1, 1, 2, 1, 2, 1, 3, 1, 4, 1, 2, 1, 1, 1, 1, 3, 1, 1, 2, 1, 4, 1, 2, 1, 5, 1, 2, 1, 1, 1, 5, 1, 1, 3, 2, 1, 1, 1, 2, 1, 3, 1, 3, 1, 1, 1, 2, 1, 3, 1, 2, 3, 1, 1, 6, 4, 4, 1, 2, 4, 2, 1, 1, 1, 1, 1, 4, 1, 1, 3 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,6 COMMENTS Ordinal transform of A017666. LINKS Antti Karttunen, Table of n, a(n) for n = 1..65537 FORMULA For all n >= 1, a(A014567(n)) = 1. For all n >= 1, a(A007691(n)) = a(A159907(n)) = a(A245775(n)) = n. 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; }; A017666(n) = (n/gcd(n, sigma(n))); v330746 = ordinal_transform(vector(up_to, n, A017666(n))); A330746(n) = v330746[n]; CROSSREFS Cf. A009194, A014567, A017666. A left inverse of following sequences: A007691, A159907, A245775. Cf. also A331175. Sequence in context: A051265 A008647 A036475 * A316555 A337531 A316556 Adjacent sequences: A330743 A330744 A330745 * A330747 A330748 A330749 KEYWORD nonn AUTHOR Antti Karttunen, Jan 11 2020 STATUS approved

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Last modified February 1 21:24 EST 2023. Contains 359997 sequences. (Running on oeis4.)