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 A076700 #22 Sep 13 2024 11:29:01
%S A076700 3,7,18,40,88,208,513,1345,3605,9965,27984,79815,230184,669541,
%T A076700 1961782,5781027,17121898,50926700,152037454,455379086,1367866472,
%U A076700 4119420084,12434683582,37613680284,113995431428,346090115288,1052421037283,3205047207003,9774084239631
%N A076700 Number of prime powers of prime numbers less than 10^n.
%H A076700 Chai Wah Wu, <a href="/A076700/b076700.txt">Table of n, a(n) for n = 1..34</a>
%e A076700 a(2) = 7 because 4, 8, 9, 25, 27, 32 and 49 are the only prime powers of prime numbers less than 100.
%t A076700 pp = Sort[ Flatten[ Table[ Prime[n]^Prime[i], {n, 1, PrimePi[ Sqrt[10^17]]}, {i, 1, PrimePi[ Floor[ Log[ Prime[n], 10^17]]]}]]]; a = {}; k = 1; Do[ While[ pp[[k]] <= 10^n, k++ ]; a = Append[a, k-1], {n, 1, 17}]
%o A076700 (Python)
%o A076700 from sympy import primepi, integer_nthroot, primerange
%o A076700 def A076700(n): return int(sum(primepi(integer_nthroot(10**n, p)[0]) for p in primerange((10**n).bit_length()))) # _Chai Wah Wu_, Sep 12 2024
%Y A076700 Cf. A053810, A075308.
%K A076700 nonn
%O A076700 1,1
%A A076700 _Zak Seidov_, Oct 26 2002
%E A076700 Edited and extended by _Robert G. Wilson v_, Oct 31 2002
%E A076700 a(18), a(19) from _Ray Chandler_, Oct 30 2008
%E A076700 a(20)-a(29) from _Donovan Johnson_, Mar 12 2013