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a(n) = gcd(A007953(n), A007954(n)).
0

%I #16 Feb 01 2024 08:31:48

%S 1,2,3,4,5,6,7,8,9,1,1,1,1,1,1,1,1,1,1,2,1,4,1,2,1,4,1,2,1,3,1,1,3,1,

%T 1,9,1,1,3,4,1,2,1,8,1,2,1,4,1,5,1,1,1,1,5,1,1,1,1,6,1,4,9,2,1,12,1,2,

%U 3,7,1,1,1,1,1,1,7,1,1,8,1,2,1,4,1,2,1,16,1,9,1,1,3

%N a(n) = gcd(A007953(n), A007954(n)).

%e a(15) = gcd(A007953(15), A007954(15)) = gcd(6,5) = 1.

%t a[n_] := GCD @@ Apply[{Plus @@ #, Times @@ #} &, {IntegerDigits[n]}]; Array[a, 100] (* _Amiram Eldar_, Jan 26 2024 *)

%Y Cf. A007953, A007954, A066308.

%K nonn,base,easy

%O 1,2

%A _Ctibor O. Zizka_, Jan 25 2024