A225648 Positions of ones in A225650, numbers n such that n and A000793(n) are coprime.

0, 1, 5, 7, 8, 9, 11, 13, 17, 19, 23, 27, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313

Offset: 1

Author

Antti Karttunen, May 12 2013

Keywords

• nonn

Comments

Contains all primes from 5 onward. Are 8, 9 and 27 only composite numbers present?

Links

• Alois P. Heinz, Table of n, a(n) for n = 1..5000

Crossrefs

Complement: A225649. Cf. also A225650.

Programs

Mathematica

b[n_, i_] := b[n, i] = Module[{p}, p = If[i < 1, 1, Prime[i]]; If[n == 0 || i < 1, 1, Max[b[n, i - 1], Table[p^j*b[n - p^j, i - 1], {j, 1, Log[p, n] // Floor}]]]]; g[n_] := b[n, If[n < 8, 3, PrimePi[Ceiling[1.328*Sqrt[n* Log[n] // Floor]]]]]; Join[{0}, Position[Table[GCD[n, g[n]], {n, 1, 500} ], 1] // Flatten] (* Jean-François Alcover, Mar 03 2016, after Alois P. Heinz *)