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Search: id:A104896
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| A104896 |
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a(0)=0; a(n) = 7*a(n-1) + 7. |
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+0
1
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| 0, 7, 56, 399, 2800, 19607, 137256, 960799, 6725600, 47079207, 329554456, 2306881199, 16148168400, 113037178807, 791260251656, 5538821761599
(list; graph; listen)
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OFFSET
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0,2
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COMMENT
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Conjecture: this is also the number of integers from 0 to 10^n - 1 that lack 0, 1 and 2 as a digit.
Number of monic irreducible polynomials of degree 1 in GF(7)[x1,...,xn]. - Max Alekseyev (maxale(AT)gmail.com), Jan 23 2006
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FORMULA
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a(n) = (7^(n+1) - 7) / 6 - Max Alekseyev (maxale(AT)gmail.com), Jan 23 2006
a(n)=7^n+a(n-1) (with a(0)=0) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 30 2009]
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EXAMPLE
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For n=1, a(1)=7+0=7; n=2, a(2)=7^2+7=56; n=3, a(3)=7^3+56=399 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Nov 30 2009]
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MAPLE
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a:=n->sum (7^j, j=1..n): seq(a(n), n=0..15); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Oct 03 2007
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CROSSREFS
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Cf. A052386, A052379, A000918, A029858, A080674.
Sequence in context: A055345 A082140 A054614 this_sequence A122996 A092315 A092318
Adjacent sequences: A104893 A104894 A104895 this_sequence A104897 A104898 A104899
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KEYWORD
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base,easy,nonn,new
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AUTHOR
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Alexandre Wajnberg (alexandre.wajnberg(AT)ulb.ac.be), Apr 24 2005
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