This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A027883 #18 Jul 08 2025 17:56:53
%S A027883 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 A027883 36,37,38,39,40,43,45,46,47,48,49,50,51,52,54,55,56,57,58,59,60,61,62,
%U A027883 63,64,65,66,67,69,71,72,73,74,75,76,77,79,80,81,82,83,84,85,87,88,89
%N A027883 Positions of primes in sequence (A246655) of primes and prime powers {p^i, i >= 1}.
%H A027883 Ray Chandler, <a href="/A027883/b027883.txt">Table of n, a(n) for n = 1..10000</a>
%F A027883 a(n) = A024620(n) - 1.
%o A027883 (Python)
%o A027883 from sympy import prime, primepi, integer_nthroot
%o A027883 def A027883(n):
%o A027883 p = prime(n)
%o A027883 return n+sum(primepi(integer_nthroot(p,k)[0]) for k in range(2,p.bit_length())) # _Chai Wah Wu_, Dec 08 2024
%Y A027883 Cf. A024620, A246655.
%K A027883 nonn,easy
%O A027883 1,2
%A A027883 _N. J. A. Sloane_
%E A027883 More terms from _Erich Friedman_.
%E A027883 Name clarified by _Ilya Gutkovskiy_, Mar 12 2020