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A185642 Nearest integer to average of distinct prime factors of n. 2
2, 3, 2, 5, 3, 7, 2, 3, 4, 11, 3, 13, 5, 4, 2, 17, 3, 19, 4, 5, 7, 23, 3, 5, 8, 3, 5, 29, 3, 31, 2, 7, 10, 6, 3, 37, 11, 8, 4, 41, 4, 43, 7, 4, 13, 47, 3, 7, 4, 10, 8, 53, 3, 8, 5, 11, 16, 59, 3, 61, 17, 5, 2, 9, 5, 67, 10, 13, 5, 71, 3, 73, 20, 4, 11, 9, 6, 79 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,1

COMMENTS

a(n) = n if and only if n is prime.

LINKS

Harvey P. Dale, Table of n, a(n) for n = 2..1000

Index to divisibility sequences

FORMULA

a(n) = round(A008472(n)/A001221(n)).

EXAMPLE

a(12) = 3, since the prime factors of 12 are 2 and 3, the average of 2 and 3 is 2.5, and the nearest integer to 2.5 is 3 (the larger number is chosen when the average is a half-integer).

MATHEMATICA

Table[Floor[Mean[FactorInteger[n][[All, 1]]]+1/2], {n, 2, 80}] (* Harvey P. Dale, Sep 23 2016 *)

PROG

(PARI) for(n=2, 79, o=omega(n); s=sum(i=1, o, factor(n)[, 1][i]); print1(round(s/o), ", "));

CROSSREFS

Cf. A001221, A008472.

Sequence in context: A218993 A067629 A079870 * A076690 A262549 A086287

Adjacent sequences:  A185639 A185640 A185641 * A185643 A185644 A185645

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Sep 11 2013

STATUS

approved

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Last modified September 23 20:42 EDT 2021. Contains 347617 sequences. (Running on oeis4.)