A300231 Filter sequence combining A001065(n) and A009194(n), the sum of proper divisors of n and gcd(n,sigma(n)).

1, 2, 2, 3, 2, 4, 2, 5, 6, 7, 2, 8, 2, 9, 10, 11, 2, 12, 2, 13, 14, 15, 2, 16, 17, 18, 19, 20, 2, 21, 2, 22, 23, 24, 19, 25, 2, 13, 26, 27, 2, 28, 2, 29, 30, 31, 2, 32, 33, 34, 12, 35, 2, 36, 26, 37, 38, 39, 2, 40, 2, 41, 42, 43, 44, 45, 2, 46, 47, 48, 2, 49, 2, 50, 51, 52, 44, 53, 2, 54, 55, 56, 2, 57, 38, 35, 30, 58, 2, 59, 60, 32, 61, 62, 63, 64

Offset: 1

Author

Antti Karttunen, Mar 01 2018

Keywords

• nonn

Comments

Restricted growth sequence transform of P(A001065(n), A009194(n)), where P(a,b) is a two-argument form of A000027 used as a Cantor pairing function N x N -> N.

Examples

			a(27) = a(35) (= 19) because A001065(27) = A001065(35) = 13 and A009194(27) = A009194(35) = 1.
		

Links

• Antti Karttunen, Table of n, a(n) for n = 1..65537

Crossrefs

Cf. A001065, A009194.

Cf. also A295885, A300223, A300226, A300229, A300230, A300232, A300233, A300235.

Programs

PARI

rgs_transform(invec) = { my(om = Map(), outvec = vector(length(invec)), u=1); for(i=1, length(invec), if(mapisdefined(om,invec[i]), my(pp = mapget(om, invec[i])); outvec[i] = outvec[pp] , mapput(om,invec[i],i); outvec[i] = u; u++ )); outvec; };
write_to_bfile(start_offset,vec,bfilename) = { for(n=1, length(vec), write(bfilename, (n+start_offset)-1, " ", vec[n])); }
A001065(n) = (sigma(n)-n);
A009194(n) = gcd(n, sigma(n));
Aux300231(n) = (1/2)*(2 + ((A001065(n)+A009194(n))^2) - A001065(n) - 3*A009194(n));
write_to_bfile(1,rgs_transform(vector(65537,n,Aux300231(n))),"b300231.txt");