A027883 - OEIS

%I #16 Dec 08 2024 11:06:27

%S 1,2,4,5,8,9,11,12,13,16,17,19,20,21,22,24,25,26,28,29,30,31,33,34,35,

%T 36,37,38,39,40,43,45,46,47,48,49,50,51,52,54,55,56,57,58,59,60,61,62,

%U 63,64,65,66,67,69,71,72,73,74,75,76,77,79,80,81,82,83,84,85,87,88,89

%N Positions of primes in sequence (A246655) of primes and prime powers {p^i, i >= 1}.

%H Ray Chandler, <a href="/A027883/b027883.txt">Table of n, a(n) for n = 1..10000</a>

%F a(n) = A024620(n) - 1.

%o (Python)

%o from sympy import prime, primepi, integer_nthroot

%o def A027883(n):

%o     p = prime(n)

%o     return n+sum(primepi(integer_nthroot(p,k)[0]) for k in range(2,p.bit_length())) # _Chai Wah Wu_, Dec 08 2024

%Y Cf. A024620, A246655.

%K nonn,easy

%O 1,2

%A _N. J. A. Sloane_.

%E More terms from _Erich Friedman_.

%E Name clarified by _Ilya Gutkovskiy_, Mar 12 2020