

A152466


a(1) = 252, a(n) is a(n1) multiplied by the smallest prime factor of a(n1)+1.


4



252, 2772, 130284, 651420, 219528540, 257067920340, 4370154645780, 292800361267260, 11023640801351071740, 13475008472558425746927448860, 5107028211099643358085503117940, 1313771981231475489737485570488833367540
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OFFSET

1,1


COMMENTS

Conjecture: this sequence will never have any numbers k where k+1 is prime. (All similar sequences that start with numbers less than 252 are known to have numbers k where k+1 is prime.)
The next few sequences that seem to be like this are 322, 622, 664, 776, and 830.  J. Lowell, Mar 25 2014


LINKS

Jon E. Schoenfield, Table of n, a(n) for n = 1..30


FORMULA

a(n) = A238642(a(n1)) (conjectured).  J. Lowell, Mar 25 2014


EXAMPLE

First term is 252. Smallest prime factor of 253 is 11, so next term is 252 * 11 = 2772.


MATHEMATICA

a = {252}; Do[AppendTo[a, a[[ 1]]*FactorInteger[a[[ 1]] + 1][[1, 1]]], {10}]; a (* Stefan Steinerberger, Dec 06 2008 *)
NestList[#*FactorInteger[#+1][[1, 1]]&, 252, 20] (* Harvey P. Dale, Apr 03 2015 *)


CROSSREFS

Cf. A238584 (ratios of consecutive terms).
Sequence in context: A166783 A104679 A117281 * A004535 A027815 A271496
Adjacent sequences: A152463 A152464 A152465 * A152467 A152468 A152469


KEYWORD

nonn


AUTHOR

J. Lowell, Dec 05 2008


EXTENSIONS

More terms from Stefan Steinerberger, Dec 06 2008
Extended by Max Alekseyev, Sep 19 2009


STATUS

approved



