cp's OEIS Frontend

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.

A350174 For k = 0, 1, 2, 3, ... write k prime(k+1) times.

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%I A350174 #17 May 26 2023 15:27:33
%S A350174 0,0,1,1,1,2,2,2,2,2,3,3,3,3,3,3,3,4,4,4,4,4,4,4,4,4,4,4,5,5,5,5,5,5,
%T A350174 5,5,5,5,5,5,5,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,6,7,7,7,7,7,7,7,7,7,7,
%U A350174 7,7,7,7,7,7,7,7,7,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,8,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9,9
%N A350174 For k = 0, 1, 2, 3, ... write k prime(k+1) times.
%C A350174 a(n) = k is the largest k with sum of primes A007504(k) <= n. - _Kevin Ryde_, Apr 19 2022
%D A350174 J.-P. Delahaye, Des suites fractales d’entiers, Pour la Science, No. 531 January 2022. Sequence g) p. 82.
%F A350174 a(n) = A083375(n+1) - 1. - _Peter Munn_, May 26 2023
%p A350174 a:=[];
%p A350174 for n from 0 to 10 do a:=[op(a), seq(n,i=1..ithprime(n+1))]; od:
%p A350174 a; # _N. J. A. Sloane_, Dec 18 2021
%o A350174 (Python)
%o A350174 from itertools import count, islice, chain
%o A350174 from sympy import prime
%o A350174 def A350174gen(): return chain.from_iterable([k]*prime(k+1) for k in count(0))
%o A350174 A350174_list = list(islice(A350174gen(),50)) # _Chai Wah Wu_, Dec 19 2021
%Y A350174 Cf. A000040, A007504.
%Y A350174 Essentially the same as A083375.
%K A350174 nonn,easy
%O A350174 0,6
%A A350174 _Michel Marcus_, Dec 18 2021