A353482 - OEIS

%I #12 Oct 13 2024 20:15:10

%S 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,1,0,

%T 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,

%U 1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1

%N a(n) = 1 if n is a squarefree semiprime of the form 4k+1, otherwise 0.

%H Antti Karttunen, <a href="/A353482/b353482.txt">Table of n, a(n) for n = 1..65537</a>

%H <a href="/index/Ch#char_fns">Index entries for characteristic functions</a>

%F For all n >= 1, a(n) <= A353477(n) <= A353480(n).

%F For all n >= 1, A353483(n) <= a(n) <= A353481(n).

%t Table[If[SquareFreeQ[n]&&PrimeOmega[n]==2&&Mod[n,4]==1,1,0],{n,150}] (* _Harvey P. Dale_, Oct 13 2024 *)

%o (PARI) A353482(n) = ((2==bigomega(n)) && (2==omega(n)) && (1==(n%4)));

%Y Characteristic function of A190299.

%Y Cf. A353477, A353480, A353481, A353483.

%K nonn

%O 1

%A _Antti Karttunen_, Apr 22 2022