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A193216 Least semiprime whose sum of prime factors equals n! 0
9, 95, 791, 7799, 85391, 1248959, 4717271, 39916679, 518918231, 6227020631, 143221477871, 1482030950111, 61460695293791, 1108907864061191, 20985558257660519, 262497321934846319, 12286155141292021799, 75419962253475839039 (list; graph; refs; listen; history; text; internal format)
OFFSET

3,1

COMMENTS

Write n! = p+q (p,q prime), p*q minimal; then a(n)=p*q. Subset of A073046.

LINKS

Table of n, a(n) for n=3..20.

EXAMPLE

a(4) = 95 because,for n=4, 4! = 24; 24 = 5 + 19 = 7 + 17 = 11 + 13; 5*19 is minimal => p*q = 5*19 = 95.

MAPLE

with(numtheory):for n from 3 to 20 do:x:=n!:id:=0:for m from 2 to 10000 while(id=0) do:p:=ithprime(m):y:=x-p:if type(y, prime)=true then z:=y*p: id:=1:printf(`%d, `, z): else fi:od:od:

CROSSREFS

Cf. A073046.

Sequence in context: A057782 A115071 A000562 * A213019 A098450 A065456

Adjacent sequences:  A193213 A193214 A193215 * A193217 A193218 A193219

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jul 18 2011

STATUS

approved

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Last modified April 27 06:52 EDT 2017. Contains 285508 sequences.