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A224693 Smallest prime p such that p > gpf(p+1) > gpf(p+2) > ... > gpf(p+n) where gpf(m) is the greatest prime factor of m. 0
3, 13, 13, 491, 2011, 12721, 12721, 109453, 586951, 173912393, 785211341, 4044619541, 315400191511, 315400191511 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

a(n) >= A100385(n+1). - Zak Seidov, Apr 17 2013

LINKS

Table of n, a(n) for n=1..14.

EXAMPLE

a(4) = 491 because 491 > 41 > 29 > 19 > 11 where:

492 = 2^2*3*41;

493 = 17*29;

494 = 2*13*19;

495 = 3^2*5*11.

MAPLE

with(numtheory):

for n from 1 to 20 do:

   ii:=0:

        for k from 1 to 10^7 while(ii=0) do:

        p:=ithprime(k): it:=0:

            for m from 1 to n do:

               x0:=factorset(p+m-1):n0:=nops(x0): x1:=factorset(p+m):n1:=nops(x1):

               if x0[n0] > x1[n1]

               then

               it:=it+1:

              else

              fi:

          od:

             if it=n

             then

             printf ( "%d %d \n", n, p):ii:=1:

             else

             fi:

        od:

    od:

CROSSREFS

Cf. A006530, A100385.

Sequence in context: A076747 A198452 A286190 * A043055 A101235 A230508

Adjacent sequences:  A224690 A224691 A224692 * A224694 A224695 A224696

KEYWORD

nonn,hard,more

AUTHOR

Michel Lagneau, Apr 15 2013

EXTENSIONS

a(10)-a(12) from Zak Seidov, Apr 17 2013

a(13)-a(14) from Donovan Johnson, Apr 26 2013

STATUS

approved

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Last modified January 22 12:55 EST 2022. Contains 350481 sequences. (Running on oeis4.)