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A338437
a(n) = n! * [x^n] Product_{k=1..n, gcd(n,k) = 1} 1 / (1 - x^k/k).
1
1, 1, 2, 9, 32, 300, 864, 17612, 74752, 1152792, 6470400, 220057992, 719622144, 40754156352, 192835098624, 4787867880000, 55181218873344, 3071730630989952, 11004144881762304, 1179255538492239744, 5720352215040000000, 253837962769406045184, 3262870639485701849088
OFFSET
0,3
MATHEMATICA
Table[n! SeriesCoefficient[Product[1/(1 - Boole[GCD[n, k] == 1] x^k/k), {k, 1, n}], {x, 0, n}], {n, 0, 22}]
CROSSREFS
KEYWORD
nonn
AUTHOR
Ilya Gutkovskiy, Oct 27 2020
STATUS
approved