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A141479
a(n) = A000111(n) + A014695(n).
2
2, 3, 3, 3, 6, 18, 63, 273, 1386, 7938, 50523, 353793, 2702766, 22368258, 199360983, 1903757313, 19391512146, 209865342978, 2404879675443, 29088885112833, 370371188237526, 4951498053124098, 69348874393137903, 1015423886506852353
OFFSET
0,1
COMMENTS
a(n) is a multiple of 3 for n > 0.
MAPLE
A000111 := proc(n) local x; n!*coeftayl( sec(x)+tan(x), x=0, n) ; end: A014695 := proc(n) local x; coeftayl( (1+2*x+2*x^2+x^3)/(1-x^4), x=0, n) ; end: A141479 := proc(n) A000111(n)+A014695(n) ; end: for n from 0 to 30 do printf("%a, ", A141479(n)) ; od; # R. J. Mathar, Sep 12 2008
PROG
(Python)
from itertools import count, islice, accumulate
def A141479_gen(): # generator of terms
yield from (2, 3)
blist = (0, 1)
for n in count(0):
yield (blist := tuple(accumulate(reversed(blist), initial=0)))[-1] + (2, 1, 1, 2)[n & 3]
A141479_list = list(islice(A141479_gen(), 40)) # Chai Wah Wu, Jun 09-11 2022
CROSSREFS
Sequence in context: A070167 A168113 A170895 * A055081 A275379 A109833
KEYWORD
nonn,easy
AUTHOR
Paul Curtz, Aug 09 2008
EXTENSIONS
Extended by R. J. Mathar, Sep 12 2008
STATUS
approved