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A343021 Positions of records in A343016. 0

%I #13 Apr 14 2021 01:17:59

%S 1,2,6,90,15120,983010

%N Positions of records in A343016.

%C Numbers k such that A343016(k) > A343016(j) for all j < k.

%C a(n) is divisible by 6 for n >= 3, by 30 for n >= 4, by 210 for n >= 5.

%C a(7) > 10^9 if it exists.

%e A343016(1) = 0.

%e A343016(2) = 1 is the first value > 0 in A343016.

%e A343016(6) = 5 is the first value > 1.

%e A343016(90) = 6 is the first value > 5.

%e A343016(15120) = 7 is the first value > 6.

%e A343016(983010) = 8 is the first value > 7.

%p R:= 1,2:

%p vmax:= 2:

%p f:= proc(n) local s, t, k;

%p s:= add(t[1]*t[2], t = ifactors(n)[2]);

%p for k from 0 do if not isprime(k*n+s) then return k fi od;

%p end proc:

%p for n from 6 by 6 to 10^6 do

%p v:= f(n);

%p if v > vmax then

%p vmax:= v;

%p R:= R, n;

%p fi

%p od:

%p R;

%t With[{s = Array[Block[{m = 0, k = Plus @@ Times @@@ FactorInteger[#]}, While[PrimeQ[# m + k], m++]; m] &, 10^6]}, Map[FirstPosition[s, #][[1]] &, Union@ FoldList[Max, s]]] (* _Michael De Vlieger_, Apr 13 2021 *)

%Y Cf. A343016.

%K nonn,more

%O 1,2

%A _J. M. Bergot_ and _Robert Israel_, Apr 02 2021

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Last modified August 24 22:45 EDT 2024. Contains 375417 sequences. (Running on oeis4.)