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A293221
a(n) = Product_{d|n, d<n} A019565(A289813(d)); a product obtained from the 1-digits present in ternary expansions of proper divisors of n.
14
1, 2, 2, 2, 2, 6, 2, 12, 6, 6, 2, 36, 2, 4, 18, 12, 2, 30, 2, 360, 12, 10, 2, 540, 6, 60, 30, 360, 2, 900, 2, 120, 30, 10, 12, 2700, 2, 4, 180, 360, 2, 540, 2, 360, 450, 6, 2, 5400, 4, 120, 30, 360, 2, 210, 30, 5040, 12, 14, 2, 1701000, 2, 84, 180, 2520, 180, 1260, 2, 840, 18, 12600, 2, 94500, 2, 140, 180, 840, 20, 18900, 2, 756000, 210, 210, 2, 23814000, 30
OFFSET
1,2
LINKS
FORMULA
a(n) = Product_{d|n, d<n} A019565(A289813(d)).
For all n >= 0, a(3^n) = A002110(n).
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
A289813(n) = { my (d=digits(n, 3)); fromdigits(vector(#d, i, if (d[i]==1, 1, 0)), 2); } \\ From _Remy Sigrist_
A293221(n) = { my(m=1); fordiv(n, d, if(d < n, m *= A019565(A289813(d)))); m; };
CROSSREFS
Cf. A019565, A289813, A293214, A293222, A293223 (restricted growth sequence transform), A293226.
Cf. also A290091.
Sequence in context: A351031 A328236 A119462 * A334512 A096625 A359072
KEYWORD
nonn,base
AUTHOR
Antti Karttunen, Oct 03 2017
STATUS
approved