A224911 - OEIS

%I #25 Nov 07 2023 08:14:34

%S 2,3,5,7,7,11,13,13,17,19,19,23,23,23,29,31,31,31,37,37,41,43,43,47,

%T 47,47,53,53,53,59,61,61,61,67,67,71,73,73,73,79,79,83,83,83,89,89,89,

%U 89,97,97,101,103,103,107,109,109,113,113,113,113,113,113,113,127,127,131,131

%N Greatest prime dividing A190339(n).

%C It appears that a(n) = A060308(n+1), verified for n <=420. - _R. J. Mathar_, Apr 28 2013

%C This appears to be a sequence of nondecreasing primes containing each prime at least once.

%C We might also consider a sequence b(n) defined by 2 followed by A006094(n): 2, 6, 15, 35, 77, 143, 221, ... . A190339(n) is also divisible by a stuttered version of b(n), namely by the sequence 2, 6, 15, 35, 35, 77, 143, 143, ... .

%F a(n) = A006530(A190339(n)).

%e a(0) = 6/2 = 3, a(1) = 15/3 = 5, a(2) = 105/15 = 7, a(3) = 105/15 = 7, a(4) = 231/21 = 11.

%p A224911 := proc(n)

%p     A006530(A190339(n)) ;

%p end proc: # _R. J. Mathar_, Apr 25 2013

%t nmax = 67; b[n_] := BernoulliB[n]; b[1] = 1/2; bb = Table[b[n], {n, 0, 2*nmax-1}]; diff = Table[Differences[bb, n], {n, 1, nmax}]; FactorInteger[#][[-1, 1]]& /@ Denominator[Diagonal[diff]] (* _Jean-François Alcover_, Mar 03 2014 *)

%Y Cf. A006530, A060308, A065091, A190339, A120303, A060265.

%K nonn

%O 0,1

%A _Paul Curtz_, Apr 19 2013