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A135687
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a(n) = a(n-1) - A004001(n)*a(n-2), a(1) = 1, a(2) = 1.
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1
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1, 1, -1, -3, 0, 12, 12, -36, -96, 120, 792, -48, -6384, -6000, 45072, 93072, -312576, -1243296, 2195040, 17114592, -9225888, -231715584, -102553152, 3141465024, 4679762304, -42442213056, -112638647616, 566436761280, 2368655123136, -6694333057344, -44592815027520
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OFFSET
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1,4
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LINKS
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FORMULA
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a(n) = a(n-1) - A004001(n)*a(n-2), with a(1) = a(2) = 1.
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MATHEMATICA
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HC[n_]:= HC[n]= If[n<3, Fibonacci[n], HC[HC[n-1]] +HC[n -HC[n-1]]]; (*A004001*)
a[n_]:= a[n]= If[n<3, 1, a[n-1] - HC[n]*a[n-2]];
Table[a[n], {n, 40}]
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PROG
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(Sage)
@cached_function
if (n<3): return fibonacci(n)
else: return HC(HC(n-1)) +HC(n -HC(n-1))
@CachedFunction
if (n<3): return 1
else: return a(n-1) - HC(n)*a(n-2)
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CROSSREFS
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KEYWORD
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sign,less
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AUTHOR
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STATUS
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approved
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