A224911 Greatest prime dividing A190339(n).

2, 3, 5, 7, 7, 11, 13, 13, 17, 19, 19, 23, 23, 23, 29, 31, 31, 31, 37, 37, 41, 43, 43, 47, 47, 47, 53, 53, 53, 59, 61, 61, 61, 67, 67, 71, 73, 73, 73, 79, 79, 83, 83, 83, 89, 89, 89, 89, 97, 97, 101, 103, 103, 107, 109, 109, 113, 113, 113, 113, 113, 113, 113, 127, 127, 131, 131

Offset: 0

Author

Paul Curtz, Apr 19 2013

Keywords

• nonn

Comments

It appears that a(n) = A060308(n+1), verified for n <=420. - R. J. Mathar, Apr 28 2013

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

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, ... .

Examples

			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.
		

Crossrefs

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

Programs

Maple

A224911 := proc(n)
    A006530(A190339(n)) ;
end proc: # R. J. Mathar, Apr 25 2013

Mathematica

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 *)

Formula

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