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A136724
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Numbers divisible by 4 which are not power of 2.
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4
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12, 20, 24, 28, 36, 40, 44, 48, 52, 56, 60, 68, 72, 76, 80, 84, 88, 92, 96, 100, 104, 108, 112, 116, 120, 124, 132, 136, 140, 144, 148, 152, 156, 160, 164, 168, 172, 176, 180, 184, 188, 192, 196, 200, 204, 208, 212, 216, 220, 224, 228, 232, 236, 240, 244, 248
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Primitive dimensions of Hadamard matrices which cannot be obtained as tensor powers of the primitive matrix 2 X 2 {{1,1},{1,-1}}
5+7=12=2+4+6, 9+11=20=2+4+6+8,.. Numbers that can be expressed as sum of two or more positive consecutive odd numbers AND as sums of two or more positive consecutive even numbers. [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 11 2010]
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MATHEMATICA
| a = {}; Do[k = 4n; If[Round[Log[k]/Log[2]] == Log[k]/Log[2], [null], AppendTo[a, k]], {n, 1, 100}]; a
z=200; lst1={}; Do[c=a; Do[c+=b; If[c<=2*z, AppendTo[lst1, c]], {b, a-2, 1, -2}], {a, 1, z, 2}]; Union@lst1; z=200; lst2={}; Do[c=a; Do[c+=b; If[c<=2*z, AppendTo[lst2, c]], {b, a-2, 1, -2}], {a, 2, z, 2}]; Union@lst2; Intersection[lst1, lst2] [From Vladimir Orlovsky (4vladimir(AT)gmail.com), May 11 2010]
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CROSSREFS
| Cf. A007299.
Sequence in context: A075078 A050421 A065201 * A112769 A097320 A204825
Adjacent sequences: A136721 A136722 A136723 * A136725 A136726 A136727
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KEYWORD
| nonn
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AUTHOR
| Artur Jasinski (grafix(AT)csl.pl), Jan 19 2008
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