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A185011 Numbers k such that P(k^2+1) < P((k+1)^2+1) where P(n) (A006530) is the largest prime factor of n. 2
1, 3, 5, 7, 8, 9, 13, 15, 18, 19, 21, 23, 25, 27, 28, 31, 32, 34, 35, 38, 39, 41, 43, 44, 47, 48, 50, 53, 55, 57, 58, 60, 64, 65, 68, 70, 73, 75, 76, 77, 78, 80, 81, 83, 86, 87, 89, 91, 93, 96, 99, 100, 105, 107, 109, 111, 112, 114, 115, 117, 119, 123, 125 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

G. C. Greubel, Table of n, a(n) for n = 1..1000

EXAMPLE

8 is in the sequence because 8^2+1 = 5*13 and 9^2+1 = 2*41 => 13 < 41.

MATHEMATICA

f[n_]:=FactorInteger[n^2+1][[-1, 1]]; Select[Range[125], f[#]<f[#+1]&]

CROSSREFS

Cf. A002522, A070089, A006530, A070087, A185002.

Sequence in context: A191257 A120212 A093670 * A175144 A183054 A188569

Adjacent sequences:  A185008 A185009 A185010 * A185012 A185013 A185014

KEYWORD

nonn

AUTHOR

Michel Lagneau, Jan 23 2012

STATUS

approved

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Last modified September 22 16:50 EDT 2020. Contains 337291 sequences. (Running on oeis4.)