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Search: id:A113541
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| A113541 |
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Numbers n such that 18n^2+1 is multiple of 19. |
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+0
2
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| 1, 18, 20, 37, 39, 56, 58, 75, 77, 94, 96, 113, 115, 132, 134, 151, 153, 170, 172, 189, 191, 208, 210, 227, 229, 246, 248, 265, 267, 284, 286, 303, 305, 322, 324, 341, 343, 360, 362, 379, 381, 398, 400, 417, 419, 436, 438, 455, 457, 474, 476, 493, 495, 512
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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Except for the first term, a(n)=19*n-a(n-1), (with a(1)=18) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009]
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FORMULA
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a(1)=1, a(2)=18 then add alternatively 2 and 7
a(n)=19*n-a(n-1), (with a(1)=18) [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)=19*2-18=20; n=3, a(3)=19*3-20=37; n=4, a(4)=19*4-37=39 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009]
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MATHEMATICA
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s={}; Do[If[IntegerQ[(18n^2+1)/19], AppendTo[s, n]], {n, 200}]; s
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CROSSREFS
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Sequence in context: A164711 A036170 A064271 this_sequence A113542 A075865 A066240
Adjacent sequences: A113538 A113539 A113540 this_sequence A113542 A113543 A113544
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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), Jan 13 2006
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EXTENSIONS
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More terms (a(22)-a(56) from Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 23 2009
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