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Search: id:A067870
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| A067870 |
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Numbers n such that n and 3^n end with the same digit. |
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+0
1
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| 7, 13, 27, 33, 47, 53, 67, 73, 87, 93, 107, 113, 127, 133, 147, 153, 167, 173, 187, 193, 207, 213, 227, 233, 247, 253, 267, 273, 287, 293, 307, 313, 327, 333, 347, 353, 367, 373, 387, 393, 407, 413, 427, 433, 447, 453, 467, 473, 487, 493, 507, 513, 527, 533
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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3^13=1594323 hence 13 is in the sequence
Except for the first term, a(n)=20*n-a(n-1), (with a(1)=13) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009]
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FORMULA
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a(2n+1)=20n-13 a(2n)=20n-7
a(n)=20*n-a(n-1), (with a(1)=13) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009]
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EXAMPLE
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for n=2, a(2)=20*2-13=27; n=3, a(3)=20*3-27=33; n=4, a(4)=20*4-33=47 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009]
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CROSSREFS
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Sequence in context: A111721 A060455 A072579 this_sequence A147258 A146718 A146646
Adjacent sequences: A067867 A067868 A067869 this_sequence A067871 A067872 A067873
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KEYWORD
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easy,nonn,base
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AUTHOR
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Benoit Cloitre (benoit7848c(AT)orange.fr), Mar 07 2002
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