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 A175944 #35 May 16 2019 18:22:32
%S A175944 1,2,2,3,3,3,5,5,5,5,5,7,7,7,7,7,7,7,11,11,11,11,11,11,11,11,11,11,11,
%T A175944 13,13,13,13,13,13,13,13,13,13,13,13,13,17,17,17,17,17,17,17,17,17,17,
%U A175944 17,17,17,17,17,17,17,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19,19
%N A175944 1 appears once, n-th prime p appears p times.
%C A175944 a(A014284(n)) = a(A175965(n)) = A018252(n). [_Reinhard Zumkeller_, Mar 18 2011]
%C A175944 This is how A063905 would have been reckoned at the beginning of the 20th century, taking the primes as given in A008578 instead of the way they are given in A000040. [_Alonso del Arte_, Sep 09 2011]
%F A175944 a(1)=1, a(n)=A063905(n-1) for n>1.
%t A175944 Join[{1}, Flatten[Table[Prime[n], {n, 8}, {Prime[n]}]]] (* _Alonso del Arte_, Sep 08 2011 based on _Robert G. Wilson v_'s program for A002024 *)
%t A175944 Join[{1},Flatten[Table[PadRight[{},n,n],{n,Prime[Range[10]]}]]] (* _Harvey P. Dale_, May 16 2019 *)
%o A175944 (Haskell)
%o A175944 a175944 n = a175944_list !! (n-1)
%o A175944 a175944_list =
%o A175944 concat $ zipWith ($) (map replicate a018252_list) a018252_list
%o A175944 -- _Reinhard Zumkeller_, Mar 18 2011
%Y A175944 Cf. A063905.
%Y A175944 Cf. A005145.
%K A175944 nonn,easy
%O A175944 1,2
%A A175944 _Juri-Stepan Gerasimov_, Oct 27 2010