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!)
A302690 a(n) is the smallest integer m such that A002828(m*n) = 2. 3

%I

%S 2,1,6,2,1,3,14,1,2,1,22,6,1,7,3,2,1,1,38,1,42,11,46,3,2,1,6,14,1,3,

%T 62,1,66,1,7,2,1,19,3,1,1,21,86,22,1,23,94,6,2,1,3,1,1,3,11,7,114,1,

%U 118,3,1,31,14,2,1,33,134,1,138,7,142,1,1,1,6,38,154,3,158

%N a(n) is the smallest integer m such that A002828(m*n) = 2.

%C All terms are squarefree.

%F a(n^2) = 2.

%e a(3) = 6 because A002828(1*3) = 3, A002828(2*3) = 3, A002828(3*3) = 1, A002828(5*3) = 4, ..., and 6 is the smallest positive multiplier leading to A002828(6*3) = 2.

%p A302690 := proc(n)

%p local k ;

%p for k from 1 do

%p if A002828(k*n) = 2 then

%p return k;

%p end if;

%p end do:

%p end proc:

%p seq(A302690(n),n=1..100) ; # _R. J. Mathar_, Apr 16 2018

%o (PARI) istwo(n:int)=my(f); if(n<3, return(n>=0); ); f=factor(n>>valuation(n, 2)); for(i=1, #f[, 1], if(bitand(f[i, 2], 1)==1&&bitand(f[i, 1], 3)==3, return(0))); 1;

%o isthree(n:int)=my(tmp=valuation(n, 2)); bitand(tmp, 1)||bitand(n>>tmp, 7)!=7;

%o a002828(n)=if(issquare(n), !!n, if(istwo(n), 2, 4-isthree(n))); \\ A002828

%o a(n) = {my(m=1); while(a002828(m*n)!=2, m++); m; } \\ _Michel Marcus_, Apr 12 2018

%Y Cf. A002828, A005117, A007913, A064680, A099304, A302694.

%K nonn

%O 1,1

%A _Juri-Stepan Gerasimov_, Apr 11 2018

%E Name corrected and more terms added by _Michel Marcus_, Apr 12 2018

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 September 20 07:46 EDT 2020. Contains 337264 sequences. (Running on oeis4.)