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Search: id:A064108
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A064108 (20^n-1)/19. +0
2
1, 21, 421, 8421, 168421, 3368421, 67368421, 1347368421, 26947368421, 538947368421, 10778947368421, 215578947368421, 4311578947368421, 86231578947368421, 1724631578947368421, 34492631578947368421 (list; graph; listen)
OFFSET

1,2

LINKS

Harry J. Smith, Table of n, a(n) for n=1,...,100

FORMULA

a(n)=20*a(n-1)+1 (with a(1)=1) [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 29 2009]

EXAMPLE

For n=2, a(2)=20*1+1=21; n=3, a(3)=20*21+1=421: n=4, a(4)=20*421+1=8421 [From Vincenzo Librandi (vincenzo.librandi(AT)tin.it), Oct 29 2009]

MAPLE

a:=n->sum(20^(n-j), j=0..n): seq(a(n), n=0..15); - Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), Feb 11 2007

PROGRAM

(PARI) for(n=1, 23, print((20^n-1)/19))

(Other) sage: [gaussian_binomial(n, 1, 20) for n in xrange(1, 17)] # [From Zerinvary Lajos (zerinvarylajos(AT)yahoo.com), May 29 2009]

(PARI) { for (n=1, 100, write("b064108.txt", n, " ", (20^n - 1)/19) ) } [From Harry J. Smith (hjsmithh(AT)sbcglobal.net), Sep 07 2009]

CROSSREFS

Adjacent sequences: A064105 A064106 A064107 this_sequence A064109 A064110 A064111

Sequence in context: A106656 A083043 A097833 this_sequence A067895 A092499 A009965

KEYWORD

easy,nonn,new

AUTHOR

Jason Earls (zevi_35711(AT)yahoo.com), Sep 17 2001

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Last modified November 9 12:23 EST 2009. Contains 166233 sequences.


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