A111406 a(n) = f(f(n+1)) - f(f(n)), where f(m) = pi(m) = A000720(m), with f(0) = 0.

0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0

Offset

0,1

Comments

Right-shifted sequence is characteristic function of prime-indexed primes (A006450). - Franklin T. Adams-Watters, Nov 17 2006

Links

Antti Karttunen, Table of n, a(n) for n = 0..65557

Index entries for characteristic functions

Prog

(PARI) A111406(n) = (primepi(primepi(n+1)) - primepi(primepi(n))); \\ Antti Karttunen, Dec 07 2017

Crossrefs

Cf. A000720, A006450.

Sequence in context: A289174 A059125 A189820 * A353463 A260445 A156731

Adjacent sequences: A111403 A111404 A111405 * A111407 A111408 A111409

Keyword

nonn

Author

N. J. A. Sloane, Nov 12 2005

Extensions

Missing right parenthesis added to the formula and case f(0) clarified by Antti Karttunen, Dec 07 2017

Status

approved