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A117582 For successive primes p, the number of ratios of the form n^2/(n^2-1) which factor into primes less than or equal to p. 2
0, 2, 5, 10, 15, 24, 34, 46, 57, 74, 90, 114, 141 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

By a theorem of Størmer, the number of ratios m/(m-1) factoring into primes only up to p is finite. A proportion of these have square denominators.

LINKS

Table of n, a(n) for n=0..12.

E. F. Ecklund and R. B. Eggleton, Prime factors of consecutive integers, Amer. Math. Monthly, 79 (1972), 1082-1089.

D. H. Lehmer, On a problem of Størmer, Ill. J. Math., 8 (1964), 57-79.

CROSSREFS

Cf. A002071, A117583.

Sequence in context: A163059 A099738 A064513 * A002134 A243971 A062472

Adjacent sequences:  A117579 A117580 A117581 * A117583 A117584 A117585

KEYWORD

hard,nonn

AUTHOR

Gene Ward Smith, Apr 02 2006

STATUS

approved

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Last modified August 25 05:19 EDT 2019. Contains 326318 sequences. (Running on oeis4.)