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A122471
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a(n)=7*a(n-1)-n for n> 0, a(0)=1.
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0
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1, 6, 40, 277, 1935, 13540, 94774, 663411, 4643869, 32507074, 227549508, 1592846545, 11149925803, 78049480608, 546346364242, 3824424549679, 26770971847737, 187396802934142, 1311777620538976, 9182443343772813
(list; graph; refs; listen; history; internal format)
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OFFSET
| 0,2
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COMMENTS
| From a quiz.
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REFERENCES
| K. Russell and P. Carter, Number Puzzles, W. Foulsham and Co. Ltd. (1993).
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FORMULA
| a(n)=36*[7+6*n+29*7^n], with n>=0 [From Paolo P. Lava (paoloplava(AT)gmail.com), Oct 01 2008]
G.f.: -(((x-3)*x+1)/((x-1)^2*(7*x-1))) [From Harvey P. Dale, June 15 2011]
a(0)=1, a(1)=6, a(2)=40, a(n)=9*a(n-1)-15*a(n-2)+7*a(n-3) [From Harvey P. Dale, June 15 2011]
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MATHEMATICA
| RecurrenceTable[{a[0]==1, a[n]==7a[n-1]-n}, a[n], {n, 0, 20}] (* or *) LinearRecurrence[{9, -15, 7}, {1, 6, 40}, 31](* From Harvey P. Dale, June 15 2011 *)
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PROG
| (PARI) a(n)=if(n>0, 7*a(n-1)-n, 1) for(n=0, 30, print1(a(n), ", "))
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CROSSREFS
| Sequence in context: A123357 A081016 A083426 * A178397 A090041 A069720
Adjacent sequences: A122468 A122469 A122470 * A122472 A122473 A122474
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KEYWORD
| nonn
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AUTHOR
| Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 14 2006
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