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A214803 Frobenius numbers of numerators and denominators of rational numbers in order of their canonical enumeration. 4
-1, -1, 1, -1, 5, -1, 3, 7, 11, -1, 19, -1, 5, 11, 17, 23, 29, -1, 13, 27, 41, -1, 7, 23, 31, 47, 55, -1, 17, 53, 71, -1, 9, 19, 29, 39, 49, 59, 69, 79, 89, -1, 43, 65, 109, -1, 11, 23, 35, 47, 59, 71, 83, 95, 107, 119, 131, -1, 25, 51, 103, 129, 155, -1, 13 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,5

COMMENTS

a(n) = A020652(n) * A038567(n) - A020652(n) - A038567(n);

for n > 1: a(A015614(n)) = A165900(n-1);

a(A002088(n)) = -1.

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..10000

Eric Weisstein's World of Mathematics, Frobenius Number.

Wikipedia, Coin problem

PROG

(Haskell)

a214803 n = a214803_list !! (n-1)

a214803_list = [x * y - x - y | y <- [1..], x <- [1..y-1], gcd x y == 1]

CROSSREFS

Sequence in context: A094136 A051996 A242303 * A225984 A074048 A244350

Adjacent sequences:  A214800 A214801 A214802 * A214804 A214805 A214806

KEYWORD

sign

AUTHOR

Reinhard Zumkeller, Jul 29 2012

STATUS

approved

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Last modified October 20 04:37 EDT 2019. Contains 328247 sequences. (Running on oeis4.)