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A122471 a(n)=7*a(n-1)-n for n> 0, a(0)=1. 0
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; text; internal format)
OFFSET

0,2

COMMENTS

From a quiz.

REFERENCES

K. Russell and P. Carter, Number Puzzles, W. Foulsham and Co. Ltd. (1993).

LINKS

Table of n, a(n) for n=0..19.

Index entries for linear recurrences with constant coefficients, signature (9, -15, 7).

FORMULA

a(n)=36*[7+6*n+29*7^n], with n>=0. - Paolo P. Lava, Oct 01 2008

G.f.: -(((x-3)*x+1)/((x-1)^2*(7*x-1))). - Harvey P. Dale, Jun 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). - Harvey P. Dale, Jun 15 2011

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](* Harvey P. Dale, Jun 15 2011 *)

PROG

(PARI) a(n)=if(n>0, 7*a(n-1)-n, 1) for(n=0, 30, print1(a(n), ", "))

CROSSREFS

Sequence in context: A123357 A081016 A083426 * A178397 A090041 A069720

Adjacent sequences:  A122468 A122469 A122470 * A122472 A122473 A122474

KEYWORD

nonn

AUTHOR

Herman Jamke (hermanjamke(AT)fastmail.fm), Sep 14 2006

STATUS

approved

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Last modified October 15 05:43 EDT 2019. Contains 328026 sequences. (Running on oeis4.)