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A280907 Least k such that cototient(k) has exactly n distinct prime factors. 0
4, 10, 42, 294, 3462, 45042, 760446, 14549526, 289194150 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Least k such that A001221(A051953(k)) = n.

LINKS

Table of n, a(n) for n=1..9.

EXAMPLE

a(1) = 4 because 4 - phi(4) = 2.

a(2) = 10 because 10 - phi(10) = 6 = 2 * 3.

a(3) = 42 because 42 - phi(42) = 30 = 2 * 3 * 5.

PROG

(PARI) a(n) = {my(k = 2); while(omega(k-eulerphi(k)) != n, k++); k; }

CROSSREFS

Cf. A001221, A051953.

Sequence in context: A149219 A222475 A194993 * A332233 A149220 A149221

Adjacent sequences:  A280904 A280905 A280906 * A280908 A280909 A280910

KEYWORD

nonn,more

AUTHOR

Altug Alkan, Jan 10 2017

STATUS

approved

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Last modified July 1 10:54 EDT 2022. Contains 354972 sequences. (Running on oeis4.)