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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A293481 Numbers with last digit greater than or equal to 5 (in base 10). 2
5, 6, 7, 8, 9, 15, 16, 17, 18, 19, 25, 26, 27, 28, 29, 35, 36, 37, 38, 39, 45, 46, 47, 48, 49, 55, 56, 57, 58, 59, 65, 66, 67, 68, 69, 75, 76, 77, 78, 79, 85, 86, 87, 88, 89, 95, 96, 97, 98, 99, 105, 106, 107, 108, 109, 115, 116, 117, 118, 119, 125, 126, 127, 128, 129 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Equivalently, numbers k such that floor(k/5) is odd.

Also numbers k such that ceiling(-k/5) is odd. - Peter Luschny, Oct 10 2017

LINKS

Colin Barker, Table of n, a(n) for n = 1..500

Index entries for linear recurrences with constant coefficients, signature (1,0,0,0,1,-1).

FORMULA

G.f.: x*(5 + x + x^2 + x^3 + x^4 + x^5)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)).

a(n) = a(n-1) + a(n-5) - a(n-6).

a(n) = A293292(n) + 5.

MAPLE

select(n -> type(ceil(-n/5), odd), [$0..130]); # Peter Luschny, Oct 10 2017

MATHEMATICA

LinearRecurrence[{1, 0, 0, 0, 1, -1}, {5, 6, 7, 8, 9, 15}, 70]

(* Second program: *)

Select[Range[129], Mod[#, 10] >= 5 &] (* Jean-Fran├žois Alcover, Oct 10 2017 *)

PROG

(MAGMA) [n: n in [0..150] | n mod 10 ge 5];

(PARI) select(k -> (k\5) % 2, vector(130, k, k)) \\ Peter Luschny, Oct 10 2017

(PARI) Vec(x*(5 + x + x^2 + x^3 + x^4 + x^5)/((1 - x)^2*(1 + x + x^2 + x^3 + x^4)) + O(x^100)) \\ Colin Barker, Oct 10 2017

(Python) [k for k in range(130) if (k//5) % 2 == 1] # Peter Luschny, Oct 10 2017

(Sage) [k for k in (0..130) if not 2.divides(k//5)] # Peter Luschny, Oct 10 2017

CROSSREFS

Complement of A293292.

Cf. A010122 (first differences, after 3).

Sequence in context: A121537 A285219 A047577 * A174138 A108401 A125298

Adjacent sequences:  A293478 A293479 A293480 * A293482 A293483 A293484

KEYWORD

nonn,base,easy

AUTHOR

Bruno Berselli, Oct 10 2017

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 November 14 02:19 EST 2019. Contains 329108 sequences. (Running on oeis4.)