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Search: id:A072077
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| A072077 |
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Number of even non-totients not exceeding 2^n. |
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+0
2
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| 0, 0, 0, 1, 2, 6, 17, 41, 94, 215, 470, 1004, 2126, 4449, 9278, 19177, 39388, 80698, 164808, 335809, 683117, 1387415, 2813664, 5700228, 11536241, 23324624
(list; graph; listen)
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OFFSET
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1,5
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EXAMPLE
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n=6: a(6)=6 because even non-totients not exceeding 64 are {14,26,34,38,50,62}.
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MATHEMATICA
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a = Table[0, {2^26}]; Do[ b = EulerPhi[n]; If[ EvenQ[b] && b < 2^27, a[[b/2]]++ ], {n, 3, 10^9}]; c = 0; k = 1; Do[ While[k <= 2^n, If[ a[[k]] == 0, c++ ]; k++ ]; Print[c], {n, 1, 17}]
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CROSSREFS
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Number of terms in A005277 <= 2^n.
Sequence in context: A064516 A001441 A037261 this_sequence A014833 A130104 A019439
Adjacent sequences: A072074 A072075 A072076 this_sequence A072078 A072079 A072080
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KEYWORD
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nonn,hard
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AUTHOR
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Labos E. (labos(AT)ana.sote.hu), Jun 13 2002
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EXTENSIONS
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Edited and extended by Robert G. Wilson v (rgwv(AT)rgwv.com), Jul 15 2002
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