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Search: id:A105365
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| A105365 |
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Rearrangement of positive integers according to parity of (prime(n)-1)/2 (see comments). |
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+0
2
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| 1, 4, 2, 6, 8, 3, 5, 9, 10, 7, 12, 11, 13, 14, 15, 17, 16, 19, 18, 20, 23, 21, 22, 29, 31, 37, 24, 25, 41, 43, 26, 27, 47, 28, 53, 30, 59, 32, 33, 61, 34, 67, 35, 71, 73, 36, 38, 39, 40, 79, 83, 42, 89, 44, 97, 45, 101, 46, 103, 107
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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a(1)=1, for n>1: if (prime(n)-1)/2 is even/odd then a(n) is the next prime/composite number.
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MATHEMATICA
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p=Prime[Range[100]]; s=Complement[Range[100], p]; bb={1}; is=1; ip=0; Do[If[OddQ[(Prime[i]-1)/2], is=is+1; bb=Append[bb, s[[is]]], ip=ip+1; bb=Append[bb, p[[ip]]]], {i, 2, 60}]; bb
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CROSSREFS
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Cf. A105366.
Sequence in context: A138947 A083412 A086399 this_sequence A077157 A114478 A134239
Adjacent sequences: A105362 A105363 A105364 this_sequence A105366 A105367 A105368
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KEYWORD
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nonn
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AUTHOR
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Zak Seidov (zakseidov(AT)yahoo.com), Apr 01 2005
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