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 A177343 #13 Sep 25 2017 15:33:04 %S A177343 1,1,1,1,3,1,2,1,4,1,2,1,3,1,4,2,4,1,1,12,1,2,3,3,2,1,2,2,1,2,2,2,1,2, %T A177343 1,3,1,1,25,1,4,2,10,1,1,1,1,3,5,1,4,10,1,7,1,8,3,2,1,1,1,4,2,5,1,1,1, %U A177343 1,1,1,1,18,1,1,1,10,2,1,1,1,6,1,16,4,2,2,3,1,1,1,3,11,1,2,1,18,1,2,1,1,1,3 %N A177343 Number of times the n-th prime occurs in A039654. %C A177343 Record values for primes up to 10000: %C A177343 n p(n) a(n) %C A177343 1 2 1 %C A177343 5 11 3 %C A177343 9 23 4 %C A177343 20 71 12 %C A177343 39 167 25 %C A177343 132 743 58 %C A177343 236 1487 62 %C A177343 417 2879 71 %C A177343 675 5039 125 %C A177343 867 6719 168 %C A177343 The function A039653(n) = sigma(n)-1 iterated in A039654 satisfies A039653(n) >= n (with equality iff n is a prime), therefore the prime p cannot appear beyond index p in A039654, and it is sufficient to count how many times p = A039654(n) with n < p, cf. Formula. - _M. F. Hasler_, Sep 25 2017 %H A177343 Franklin T. Adams-Watters, <a href="/A177343/b177343.txt">Table of n, a(n) for n=1..1229 (primes through 10000)</a> %F A177343 a(n) = 1 + # { k < prime(n) | A039654(k) = prime(n) } . - _M. F. Hasler_, Sep 25 2017 %o A177343 (PARI) a(n)=sum(k=2,n=prime(n),A039654(k)==n) \\ _M. F. Hasler_, Sep 25 2017 %Y A177343 Cf. A039654, A039653, A292112, A292113. %K A177343 nonn %O A177343 1,5 %A A177343 _Franklin T. Adams-Watters_, May 06 2010