The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 Hints (Greetings from The On-Line Encyclopedia of Integer Sequences!)
 A316434 a(n) = a(pi(n)) + a(n-pi(n)) with a(1) = a(2) = 1. 5
 1, 1, 2, 2, 3, 4, 4, 4, 5, 6, 7, 7, 8, 8, 9, 10, 10, 11, 11, 11, 12, 12, 13, 14, 15, 15, 16, 16, 17, 17, 18, 19, 19, 20, 21, 22, 22, 22, 23, 23, 24, 25, 25, 25, 26, 27, 28, 28, 29, 30, 31, 31, 32, 32, 33, 33, 34, 35, 35, 35, 36, 36, 37, 38, 39, 39, 39, 40, 41, 42, 42, 42, 43, 44, 44 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS This sequence hits every positive integer. LINKS Robert Israel, Table of n, a(n) for n = 1..10000 Altug Alkan, A plot of a(n)/n Altug Alkan and Orhan Ozgur Aybar, On a Family of Sequences Related to Prime Counting Function, International Journal of Statistics and Probability Vol. 7, No. 6; 2018. Rémy Sigrist, C++ program for A316434 FORMULA a(n) = a(A000720(n)) + a(A062298(n)) with a(1) = a(2) = 1. a(n+1) - a(n) = 0 or 1 for all n >= 1. MAPLE f:= proc(n) option remember: local p;      p:= numtheory:-pi(n);      procname(p) + procname(n-p) end proc: f(1):= 1: f(2):= 1: map(f, [\$1..100]); # Robert Israel, Jul 03 2018 MATHEMATICA a[1]=a[2]=1; a[n_] := a[n] = a[PrimePi[n]] + a[n - PrimePi[n]]; Array[a, 75] (* Giovanni Resta, Nov 02 2018 *) PROG (PARI) q=vector(75); for(n=1, 2, q[n] = 1); for(n=3, #q, q[n] = q[primepi(n)] + q[n-primepi(n)]); q (C++) See Links section. (Python) from sympy import primepi def A316434(n):     pp = primepi(n)     return 1 if n == 1 or n == 2 else A316434(pp) + A316434(n-pp) # Chai Wah Wu, Nov 02 2018 CROSSREFS Cf. A000720, A062298. Sequence in context: A086841 A076502 A076897 * A066997 A006165 A078881 Adjacent sequences:  A316431 A316432 A316433 * A316435 A316436 A316437 KEYWORD nonn AUTHOR Altug Alkan, Jul 02 2018 STATUS approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

Last modified September 21 14:54 EDT 2020. Contains 337272 sequences. (Running on oeis4.)