cp's OEIS Frontend

A344595 Numbers k such that A011772(k) > A344878(k) and A011772(k) is a divisor of A344875(k).

%I A344595 #9 Jun 05 2021 16:42:55
%S A344595 900,1260,1302,1560,2100,3906,4440,6300,6552,6669,9680,11544,12987,
%T A344595 15368,18981,19240,19880,24120,26208,35784,36080,42680,46104,57720,
%U A344595 59040,59640,62238,62244,71136,74592,76840,79376,81872,84700,101680,103730,108500,124488,128040,145188,160160,168020,171740,178920,185724,201608
%N A344595 Numbers k such that A011772(k) > A344878(k) and A011772(k) is a divisor of A344875(k).
%C A344595 Numbers k for which A344973(k) = 0 and A344976(k) < 0.
%C A344595 It seems that in these cases, by necessity A011772(k) < A344875(k), i.e., A011772(k) is a proper divisor of A344875(k).
%C A344595 Has many terms common with A344694.
%o A344595 (PARI)
%o A344595 A011772(n) = { if(n==1, return(1)); my(f=factor(if(n%2, n, 2*n)), step=vecmax(vector(#f~, i, f[i, 1]^f[i, 2]))); forstep(m=step, 2*n, step, if(m*(m-1)/2%n==0, return(m-1)); if(m*(m+1)/2%n==0, return(m))); }; \\ From A011772
%o A344595 A344875(n) = { my(f=factor(n)~); prod(i=1, #f, (f[1, i]^(f[2, i]+(2==f[1, i]))-1)); };
%o A344595 A344878(n) = if(1==n,n, my(f=factor(n)~); lcm(vector(#f, i, (f[1, i]^(f[2, i]+(2==f[1, i]))-1))));
%o A344595 isA344595(n) = { my(u=A011772(n)); (u>A344878(n)&&0==(A344875(n)%u)); };
%Y A344595 Cf. A011772, A344694, A344875, A344878, A344973, A344976.
%Y A344595 Intersection of A024619, A344974 and A344977.
%Y A344595 Intersection of A344975 and A344977.
%K A344595 nonn
%O A344595 1,1
%A A344595 _Antti Karttunen_, Jun 05 2021