A255324 Difference between the n-th Ludic number and the n-th noncomposite number: a(n) = A003309(n) - A008578(n).

0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 0, 6, 4, 2, 4, 6, 8, 8, 10, 10, 12, 16, 12, 14, 18, 18, 18, 18, 20, 22, 30, 22, 26, 24, 34, 26, 28, 24, 30, 42, 38, 42, 42, 36, 40, 38, 40, 36, 34, 38, 48, 50, 48, 60, 56, 56, 66, 62, 66, 64, 72, 76, 68, 70, 72, 76, 80, 76, 78, 72, 72, 78, 74, 70, 72, 84, 84, 86, 84, 92, 88, 84, 88, 86, 94, 96, 98, 104

Offset: 1

Author

Antti Karttunen, Feb 23 2015

Keywords

• nonn

Links

• Antti Karttunen, Table of n, a(n) for n = 1..14000

Crossrefs

Cf. A255325 (the same terms halved).

Cf. A032600, A003309, A008578, A255421, A255422.

Programs

Mathematica

t = Range[2, 1000];
A003309 = {1};
While[Length[t]>0, k = t[[1]]; AppendTo[A003309, k]; t = Drop[t, {1, -1, k}]];
a[n_] := If[n == 1, 0, A003309[[n]] - Prime[n - 1]];
Array[a, Length[A003309]] (* Jean-François Alcover, Jan 08 2022, after Ray Chandler in A003309 *)

Scheme

(define (A255324 n) (- (A003309 n) (A008578 n)))

Formula

a(n) = A003309(n) - A008578(n).

a(n) = 2*A255325(n).