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A122039
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a(n) = 2*a(n-1) - n + 4 for n>1, a(1)=1.
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0
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1, 4, 9, 18, 35, 68, 133, 262, 519, 1032, 2057, 4106, 8203, 16396, 32781, 65550, 131087, 262160, 524305, 1048594, 2097171, 4194324, 8388629, 16777238, 33554455, 67108888, 134217753, 268435482, 536870939, 1073741852, 2147483677
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,2
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COMMENTS
| From a quiz.
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LINKS
| C. P. Simoes, Teste de Desempenho Mental.
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FORMULA
| a(n)=A083706(n-1). [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 02 2008]
a(n)=2^n+n-2, with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Oct 01 2008]
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EXAMPLE
| 1x2 + (2) = 4; 4x2 + (1) = 9; 9x2 + (0) = 18; 18x2 + (-1) = 35; 35x2 + (-2) = 68
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PROG
| (PARI) a(n)=if(n>1, 2*a(n-1)+(4-n), 1) for(n=1, 40, print1(a(n), ", "))
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CROSSREFS
| Sequence in context: A019453 A038089 A027053 * A083706 A074896 A015713
Adjacent sequences: A122036 A122037 A122038 * A122040 A122041 A122042
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KEYWORD
| nonn
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AUTHOR
| Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 14 2006
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