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A173561 a(n)^2+1 factors with largest prime p and p/a(n) is smaller than for any previous integer's result. 0
1, 3, 7, 38, 47, 57, 157, 239, 829, 882, 993, 1772, 2673, 2917, 2943 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

This is an infinite sequence, since the solutions to the Pell equations for primes p=4n+1 will give ratios with limit 0. For example, the entry 7 satisfies 7^2 - 2*5^2 = -1 and the ratio is 5/7. However, not all entrys are given by this technique.

LINKS

Table of n, a(n) for n=1..15.

EXAMPLE

For n=3, a(3)=7 because 7^2+1=2*5*5 and 5/7 is smaller than all previous results.

CROSSREFS

Sequence in context: A152560 A162926 A042895 * A258840 A209029 A169741

Adjacent sequences:  A173558 A173559 A173560 * A173562 A173563 A173564

KEYWORD

nonn

AUTHOR

M. J. Knight (melknightdr(AT)verizon.net), Feb 21 2010

STATUS

approved

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Last modified March 25 10:23 EDT 2019. Contains 321470 sequences. (Running on oeis4.)