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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A328232 Numbers whose arithmetic derivative (A003415) is a primorial number, including cases where it is the first primorial, A002110(0) = 1. 4

%I

%S 2,3,5,7,9,11,13,17,19,23,29,31,37,41,43,47,53,59,61,67,71,73,79,83,

%T 89,97,101,103,107,109,113,127,131,137,139,149,151,157,161,163,167,

%U 173,179,181,191,193,197,199,209,211,221,223,227,229,233,239,241,251,257,263,269,271,277,281,283,293,307,311,313,317

%N Numbers whose arithmetic derivative (A003415) is a primorial number, including cases where it is the first primorial, A002110(0) = 1.

%C Numbers n such that A327859(n) = A276086(A003415(n)) is a prime.

%H Antti Karttunen, <a href="/A328232/b328232.txt">Table of n, a(n) for n = 1..10000</a>

%H <a href="/index/Pri#primorial_numbers">Index entries for sequences related to primorial numbers</a>

%o (PARI)

%o A003415(n) = if(n<=1, 0, my(f=factor(n)); n*sum(i=1, #f~, f[i, 2]/f[i, 1]));

%o A276086(n) = { my(i=0,m=1,pr=1,nextpr); while((n>0),i=i+1; nextpr = prime(i)*pr; if((n%nextpr),m*=(prime(i)^((n%nextpr)/pr));n-=(n%nextpr));pr=nextpr); m; };

%o A327859(n) = A276086(A003415(n));

%o isA328232(n) = isprime(A327859(n));

%Y Cf. A002110, A003415, A024451 (arith. deriv. of primorials), A068346, A276086, A327859, A328233.

%Y Union of A000040 and A327978 (gives the composite terms).

%Y Differs from A189710 for the first time by having term a(39) = 161, which is not included in A189710, while A189710(44) = 185 is the first term in latter that is not included here.

%K nonn

%O 1,1

%A _Antti Karttunen_, Oct 09 2019

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.

License Agreements, Terms of Use, Privacy Policy. .

Last modified June 4 08:18 EDT 2020. Contains 334825 sequences. (Running on oeis4.)