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.

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, 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, 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

Offset

1,4

Links

Antti Karttunen, Table of n, a(n) for n = 1..6561

Formula

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

Prog

(PARI)
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
A289814(n) = { my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==2, 1, 0)), 2); } \\ From _Remy Sigrist_
A293222(n) = { my(m=1); fordiv(n, d, if(d < n, m *= A019565(A289814(d)))); m; };

Crossrefs

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

Sequence in context: A295279 A316784 A284974 * A305008 A245037 A161311

Adjacent sequences: A293219 A293220 A293221 * A293223 A293224 A293225

Keyword

nonn,base

Author

Antti Karttunen, Oct 03 2017

Status

approved