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A320957
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a(n) = (1/6)*n!*[x^n] (2 + sec(3*x) + tan(3*x) + 3*sec(x) + 3*tan(x)).
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3
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1, 1, 2, 10, 70, 656, 7442, 99280, 1515190, 26038016, 497227682, 10445708800, 239394707110, 5943715352576, 158922998335922, 4552807055288320, 139123511874743830, 4517007538261262336, 155283277843358756162, 5634815061983539363840, 215234080472925069593350
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OFFSET
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0,3
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COMMENTS
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See A320956 for motivation and definitions.
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LINKS
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MAPLE
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egf := 2 + sec(3*x) + tan(3*x) + 3*sec(x) + 3*tan(x):
ser := series(egf, x, 22): seq((1/6)*n!*coeff(ser, x, n), n=0..20);
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MATHEMATICA
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m = 20;
egf = 2 + Sec[3x] + Tan[3x] + 3 Sec[x] + 3 Tan[x];
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PROG
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(PARI) sectan(x) = 1/cos(x) + tan(x);
my(x='x+O('x^25)); Vec(serlaplace(2 + sectan(3*x) + 3*sectan(x)))/6 \\ Michel Marcus, Aug 19 2021
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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