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A103634 a(1) = 0; a(n) = the least k such that ((n+1)(n+2)(n+3)...(n+k))/((n-1)(n-2)(n-3)...(n-k)) is an integer (see A092935). 1
0, 1, 1, 2, 3, 4, 3, 6, 7, 8, 9, 10, 9, 12, 13, 12, 15, 16, 15, 18, 17, 20, 21, 22, 23, 24, 25, 26, 25, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 39, 42, 43, 42, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 63, 66, 67, 68, 69, 70, 71 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,4

LINKS

Table of n, a(n) for n=1..73.

PROG

(PARI) { a(n) = local(p, q, r); p=1; q=1; for(k=1, n, p*=n+k; q*=n-k; r=gcd(p, q); p\=r; q\=r; if(q==1, return(k))) }

CROSSREFS

Cf. A092935.

Sequence in context: A116550 A283165 A116991 * A255046 A098596 A217536

Adjacent sequences:  A103631 A103632 A103633 * A103635 A103636 A103637

KEYWORD

nonn

AUTHOR

Max Alekseyev, Feb 11 2005

STATUS

approved

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Last modified October 22 09:56 EDT 2019. Contains 328315 sequences. (Running on oeis4.)