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Search: id:A006368
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| A006368 |
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If n even then 3n/2 otherwise nearest integer to 3n/4.
(Formerly M2249)
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+0
9
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| 0, 1, 3, 2, 6, 4, 9, 5, 12, 7, 15, 8, 18, 10, 21, 11, 24, 13, 27, 14, 30, 16, 33, 17, 36, 19, 39, 20, 42, 22, 45, 23, 48, 25, 51, 26, 54, 28, 57, 29, 60, 31, 63, 32, 66, 34, 69, 35, 72, 37, 75, 38, 78, 40, 81, 41, 84, 43, 87, 44, 90, 46, 93, 47, 96, 49, 99, 50, 102, 52, 105, 53
(list; graph; listen)
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OFFSET
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0,3
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COMMENT
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a(n)=-a(-n).
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REFERENCES
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S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
R. K. Guy, Unsolved Problems in Number Theory, E17.
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LINKS
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S. Plouffe, Approximations de S\'{e}ries G\'{e}n\'{e}ratrices et Quelques Conjectures}, Dissertation, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
S. Plouffe, 1031 Generating Functions and Conjectures, Universit\'{e} du Qu\'{e}bec \`{a} Montr\'{e}al, 1992.
Index entries for sequences that are permutations of the natural numbers
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FORMULA
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G.f.: x(1+3x+x^2+3x^3+x^4)/((1-x^2)(1-x^4)). a(2n)=3n, a(4n+1)=3n+1, a(4n-1)=3n-1. - Michael Somos, Jul 23, 2002
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EXAMPLE
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9 is odd so a(9)=round(3*9/4)=round(7-1/4)=7.
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MAPLE
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A006368:=(1+3*z+z**2+3*z**3+z**4)/(1+z**2)/(z-1)**2/(1+z)**2; [Conjectured by S. Plouffe in his 1992 dissertation.]
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PROGRAM
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(PARI) a(n)=(3*n+n%2)\(2+n%2*2)
(PARI) a(n)=if(n%2, round(3*n/4), 3*n/2)
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CROSSREFS
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Inverse mapping to A006369.
Cf. A028397.
Sequence in context: A064789 A093050 A054089 this_sequence A105354 A094077 A091018
Adjacent sequences: A006365 A006366 A006367 this_sequence A006369 A006370 A006371
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KEYWORD
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nonn,nice,easy
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AUTHOR
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njas and J. H. Conway (conway(AT)math.princeton.edu)
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EXTENSIONS
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More terms from Jason Earls (zevi_35711(AT)yahoo.com), Jul 12 2001
Edited by Michael Somos, Jul 23, 2002
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