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Search: id:A127431
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| A127431 |
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a(1)=1. a(n) = number of earlier terms a(k), 1<=k<=n-1, such that (k+n) is divisible by a(k). |
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+0
3
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| 1, 1, 2, 2, 3, 3, 4, 3, 5, 5, 4, 4, 7, 3, 6, 8, 5, 5, 6, 5, 8, 8, 5, 6, 10, 5, 8, 8, 9, 7, 7, 8, 9, 9, 8, 9, 12, 5, 8, 12, 8, 9, 10, 7, 13, 9, 13, 11, 10, 7, 9, 12, 11, 9, 11, 10, 18, 8, 8, 10, 16, 10, 9, 12, 11, 11, 14, 13, 13, 12, 10, 15, 12, 10, 15, 11, 15, 12, 11, 13, 14, 12, 12, 13, 18, 9, 14
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OFFSET
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1,3
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EXAMPLE
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(1+11) is a multiple of a(1)=1; (2+11) is a multiple of a(2)=1; (3+11) is a multiple of a(3)=2; and (9+11) is a multiple of a(9)=5. These four cases are the only cases where (k+n) is divisible by a(k), for 1<=k<=10. So a(11) = 4.
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MATHEMATICA
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f[l_List] := Block[{n = Length[l] + 1}, Append[l, Count[Table[Mod[k + n, l[[k]]], {k, n - 1}], 0]]]; Nest[f, {1}, 86] (*Chandler*)
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CROSSREFS
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Cf. A127432, A127433.
Adjacent sequences: A127428 A127429 A127430 this_sequence A127432 A127433 A127434
Sequence in context: A067539 A138099 A110266 this_sequence A027833 A110676 A117171
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Jan 14 2007
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EXTENSIONS
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Extended by Ray Chandler (rayjchandler(AT)sbcglobal.net), Jan 22 2007
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