login
The OEIS is supported by the many generous donors to the OEIS Foundation.

 

Logo
Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A345945 Numbers k that have such a proper divisor d for which A002034(d) = A002034(k). 4

%I #10 Jul 04 2021 15:55:04

%S 6,8,10,12,14,15,18,20,21,22,24,26,28,30,33,34,35,36,38,39,40,42,44,

%T 45,46,48,50,51,52,54,55,56,57,58,60,62,63,64,65,66,68,69,70,72,74,75,

%U 76,77,78,80,81,82,84,85,86,87,88,90,91,92,93,94,95,96,98,99,100,102,104,105,106,108,110,111,112,114,115,116,117

%N Numbers k that have such a proper divisor d for which A002034(d) = A002034(k).

%H <a href="/index/Fa#factorial">Index entries for sequences related to factorial numbers</a>

%e 21 = 3*7 is present because A002034(21) = 7 = A002034(7).

%o (PARI)

%o A002034(n) = if(1==n,n,my(s=factor(n)[, 1], k=s[#s], f=Mod(k!, n)); while(f, f*=k++); (k)); \\ After code in A002034.

%o A345950(n) = { my(x=A002034(n)); fordiv(n,d,if(A002034(d)==x,return(d==n))); };

%o isA345945(n) = !A345950(n);

%Y Cf. A002034, A345944 (complement).

%Y Positions of terms > 1 in A345935.

%Y Union of A024619 and A345946.

%Y Cf. also A344882.

%K nonn

%O 1,1

%A _Antti Karttunen_, Jul 04 2021

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

License Agreements, Terms of Use, Privacy Policy. .

Last modified September 3 02:34 EDT 2024. Contains 375649 sequences. (Running on oeis4.)