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A078433 Number of permutations p of 1,2,...,n such that the numerator of the continued fraction [p(1); p(2),...,p(n)] is prime. 2
0, 2, 2, 10, 30, 124, 992, 5700, 39844, 366172, 3587856, 38861778, 435816838 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..13.

PROG

(PARI) a(n)=sum(i=1, n!, isprime(contfracpnqn(numtoperm(n, i))[1, 1]))

CROSSREFS

Cf. A078432, A078431.

Sequence in context: A200949 A001885 A300641 * A059494 A052647 A232974

Adjacent sequences:  A078430 A078431 A078432 * A078434 A078435 A078436

KEYWORD

more,nonn

AUTHOR

Reiner Martin (reinermartin(AT)hotmail.com), Dec 30 2002

EXTENSIONS

a(10)-a(11) from Robert Gerbicz, Nov 21 2010

a(12)-a(13) from Robert Gerbicz, Nov 27 2010

STATUS

approved

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Last modified March 19 23:02 EDT 2019. Contains 321343 sequences. (Running on oeis4.)