login
This site is supported by donations to The OEIS Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A130130 a(0)=0, a(1)=1, a(n)=2 for n >= 2. 19
0, 1, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,3

COMMENTS

a(n) is also total number of positive integers below 10^(n+1) requiring 9 positive cubes in their representation as sum of cubes (cf. Dickson, 1939).

A061439(n) + A181375(n) + A181377(n) + A181379(n) + A181381(n) + A181400(n) + A181402(n) + A181404(n) + a(n) = A002283(n).

a(n) = number of obvious divisors of n. The obvious divisors of n are the numbers 1 and n. - Jaroslav Krizek, Mar 02 2009

Number of colors needed to paint n adjacent segments on a line. - Jaume Oliver Lafont, Mar 20 2009

a(n) = ceiling(n-th nonprimes/n) = ceiling(A018252(n)/A000027(n)) for n >= 1. Numerators of (A018252(n)/A000027(n)) in A171529(n), denominators of (A018252(n)/A000027(n)) in A171530(n). a(n) = A171624(n) + 1 for n >= 5. - Jaroslav Krizek, Dec 13 2009

a(n) is also the continued fraction for sqrt(1/2). - Enrique Pérez Herrero, Jul 12 2010

For n >= 1, a(n) = minimal number of divisors of any n-digit number. See A066150 for maximal number of divisors of any n-digit number. - Jaroslav Krizek, Jul 18 2010

Central terms in the triangle A051010. - Reinhard Zumkeller, Jun 27 2013

LINKS

Table of n, a(n) for n=0..97.

Leonard Eugene Dickson,  All integers except 23 and 239 are sums of eight cubes, Bulletin of the American Mathematical Society 45 (1939), p. 588-591.

Eric W. Weisstein, MathWorld -- Waring's Problem.

Index entries for linear recurrences with constant coefficients, signature (1).

FORMULA

a(n) = 2*[(n+2) mod (n+1)] - [n!^2 mod (n+1)]*[(n+1)!^2 mod (n+2)], with n>=0. - Paolo P. Lava, Aug 28 2007

G.f.: x*(1+x)/(1-x)=x*(1-x^2)/(1-x)^2. - Jaume Oliver Lafont, Mar 20 2009

a(n) = A000005(n) - A070824(n) for n >= 1.

MATHEMATICA

A130130[0]:=0; A130130[1]:=1; A130130[n_]:=2; (* Enrique Pérez Herrero, Jul 12 2010 *)

A130130[n_]:=ContinuedFraction[Sqrt[1/2], n+1][[n+1]] (* Enrique Pérez Herrero, Jul 12 2010 *)

Join[{0, 1}, LinearRecurrence[{1}, {2}, 96]] (* Ray Chandler, Sep 23 2015 *)

PROG

(PARI) a(n)=min(n, 2) \\ Charles R Greathouse IV, Jun 01 2011

(Haskell)

a130130 = min 2

a130130_list = 0 : 1 : repeat 2  -- Reinhard Zumkeller, Jun 27 2013

CROSSREFS

Cf. A158411. - Jaume Oliver Lafont, Mar 20 2009

Sequence in context: A211665 A065685 A084100 * A046698 A007395 A036453

Adjacent sequences:  A130127 A130128 A130129 * A130131 A130132 A130133

KEYWORD

nonn,easy

AUTHOR

Paul Curtz, Aug 01 2007

STATUS

approved

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified October 17 22:21 EDT 2019. Contains 328134 sequences. (Running on oeis4.)