A111406 - OEIS

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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

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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.