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 A097944 #28 Oct 24 2019 17:24:18 %S A097944 1,1,1,1,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,2,3,3,3,3,3,3,3,3,3, %T A097944 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3, %U A097944 3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3,3 %N A097944 Number of digits in n-th prime. %C A097944 For primes p <= n sum(a(n)) -> n/2 and n-> inf. %H A097944 Reinhard Zumkeller, <a href="/A097944/b097944.txt">Table of n, a(n) for n = 1..10000</a> %F A097944 a(n) = (log n + log log n)/(log 10) + O(1). %F A097944 a(n) = A055642(A000040(n)). - _Reinhard Zumkeller_, Apr 08 2012 %F A097944 a(n) = A068670(n) - A068670(n-1). - _M. F. Hasler_, Oct 24 2019 %e A097944 The first 4 primes are 2,3,5,7. These are 1-digit numbers so the first 4 entries in the table are 1's. %t A097944 a[n_]:=StringLength[ToString[Prime[n]]]; (* _Vladimir Joseph Stephan Orlovsky_, Dec 03 2008 *) %t A097944 IntegerLength[Prime[Range[110]]] (* _Harvey P. Dale_, Oct 04 2012 *) %o A097944 (PARI) a(n)=#Str(prime(n)) %o A097944 (PARI) A097944(n)=logint(prime(n),10)+1 \\ _M. F. Hasler_, Oct 24 2019 %o A097944 (Haskell) %o A097944 a097944 = a055642 . a000040 -- _Reinhard Zumkeller_, Apr 08 2012 %Y A097944 Cf. A060417, A068670 (partial sums). %K A097944 nonn,base,easy %O A097944 1,5 %A A097944 _Cino Hilliard_, Sep 05 2004