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A293222 a(n) = Product_{d|n, d<n} A019565(A289814(d)); a product obtained from the 2-digits present in ternary expansions of proper divisors of n. 13

%I #7 Oct 18 2017 00:56:12

%S 1,1,1,2,1,2,1,2,1,4,1,6,1,6,2,12,1,6,1,4,3,4,1,36,2,2,1,12,1,36,1,36,

%T 2,12,6,30,1,10,1,240,1,180,1,20,6,20,1,1620,3,60,6,60,1,30,4,72,5,4,

%U 1,360,1,2,15,72,2,180,1,36,10,144,1,2700,1,2,90,20,6,180,1,720,1,4,1,540,12,6,2,720,1,900,3,100,1,20,10,16200,1,60,6

%N a(n) = Product_{d|n, d<n} A019565(A289814(d)); a product obtained from the 2-digits present in ternary expansions of proper divisors of n.

%H Antti Karttunen, <a href="/A293222/b293222.txt">Table of n, a(n) for n = 1..6561</a>

%F a(n) = Product_{d|n, d<n} A019565(A289814(d)).

%o (PARI)

%o A019565(n) = {my(j,v); factorback(Mat(vector(if(n, #n=vecextract(binary(n), "-1..1")), j, [prime(j), n[j]])~))}; \\ This function from _M. F. Hasler_

%o A289814(n) = { my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); } \\ From _Remy Sigrist_

%o A293222(n) = { my(m=1); fordiv(n,d,if(d < n,m *= A019565(A289814(d)))); m; };

%Y Cf. A019565, A289814, A293221, A293224 (restricted growth sequence transform), A293226.

%K nonn,base

%O 1,4

%A _Antti Karttunen_, Oct 03 2017

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Last modified March 28 18:04 EDT 2024. Contains 371254 sequences. (Running on oeis4.)