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A284720
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Number of indecomposable permutations avoiding the vincular pattern 1 2_ 3_.
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0
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1, 1, 3, 11, 43, 179, 801, 3861, 19991, 110679, 652127, 4071179, 26823449, 185864737, 1350279523, 10256563803, 81258332915, 669990127123, 5737790656217, 50947129880373, 468260045596695, 4448381809651895, 43618802110132167, 440918949811405787
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OFFSET
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1,3
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LINKS
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MATHEMATICA
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Table[BellB[n] - Sum[BellB[k], {k, 0, n-2}], {n, 1, 30}] (* Vaclav Kotesovec, Apr 02 2017 *)
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PROG
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(Python)
from sympy import bell
print([bell(n) - sum(bell(k) for k in range(n - 1)) for n in range(1, 30)]) # Indranil Ghosh, Apr 03 2017 (translated from Mathematica)
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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