

A031441


a(0) = 3; for n > 0, a(n) is the greatest prime factor of PreviousPrime(a(n1))*a(n1)1 where PreviousPrime(prime(k))=prime(k1).


5



3, 5, 7, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23, 109, 17, 11, 19, 23
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OFFSET

0,1


LINKS

Harvey P. Dale, Table of n, a(n) for n = 0..1000


EXAMPLE

To get a(3) we compute PreviousPrime(7)=5, 5*71=34, greatest prime factor of 34 is 17, so a(3)=17.


MATHEMATICA

a[0] = 3; a[n_] := a[n] = FactorInteger[ NextPrime[ a[n1], 1]*a[n1]  1][[1, 1]]; Table[a[n], {n, 0, 66}] (* JeanFrançois Alcover, Mar 09 2012 *)
NestList[FactorInteger[NextPrime[#, 1]*#1][[1, 1]]&, 3, 70] (* Harvey P. Dale, Dec 13 2012 *)


CROSSREFS

Cf. A034970, A031442.
Sequence in context: A078683 A099863 A112092 * A078150 A276044 A114265
Adjacent sequences: A031438 A031439 A031440 * A031442 A031443 A031444


KEYWORD

nonn,easy,nice


AUTHOR

Yasutoshi Kohmoto


EXTENSIONS

More terms from James A. Sellers


STATUS

approved



