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

 

Logo

Many excellent designs for a new banner were submitted. We will use the best of them in rotation.

Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A131242 Sum {0<=k<=n, floor(k/10)} (Partial sums of A059995). 15
0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 33, 36, 39, 42, 45, 48, 51, 54, 57, 60, 64, 68, 72, 76, 80, 84, 88, 92, 96, 100, 105, 110, 115, 120, 125, 130, 135, 140, 145, 150, 156, 162, 168, 174, 180, 186, 192, 198 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,12

COMMENTS

Complementary with A130488 regarding triangular numbers, in that A130488(n)+10*a(n)=n(n+1)/2=A000217(n).

LINKS

Table of n, a(n) for n=0..67.

FORMULA

a(n)=(1/2)*floor(n/10)*(2n-8-10*floor(n/10)).

a(n)=A059995(n)*(2n-8-10*A059995(n))/2.

a(n)=(1/2)*A059995(n)*(n-8+A010879(n)).

a(n)=(n-A010879(n))*(n+A010879(n)-8)/20.

G.f.: x^10/((1-x^10)(1-x)^2).

From Philippe Deléham, Mar 27 2013: (Start)

a(10n) = A051624(n).

a(10n+1) = A135706(n).

a(10n+2) = A147874(n+1).

a(10n+3) = 2*A005476(n).

a(10n+4) = A033429(n).

a(10n+5) = A202803(n).

a(10n+6) = A168668(n).

a(10n+7) = 2*A147875(n).

a(10n+8) = A135705(n).

a(10n+9) = A124080(n). (End)

EXAMPLE

As square array :

  0,   0,   0,   0,   0,   0,   0,   0,   0,   0

  1,   2,   3,   4,   5,   6,   7,   8,   9,  10

12,  14,  16,  18,  20,  22,  24,  26,  28,  30

33,  36,  39,  42,  45,  48,  51,  54,  57,  60

64,  68,  72,  76,  80,  84,  88,  92,  96, 100

105, 110, 115, 120, 125, 130, 135, 140, 145, 150

156, 162, 168, 174, 180, 186, 192, 198, 204, 210

... - Philippe Deléham, Mar 27 2013

CROSSREFS

Cf. A059995, A010879, A002266, A130488.

Cf. Similar sequences: A000217, A002620, A130518, A130519, A130520, A174709, A174738, A118729, A218470.

Sequence in context: A144688 A164836 A032518 * A008728 A179052 A083292

Adjacent sequences:  A131239 A131240 A131241 * A131243 A131244 A131245

KEYWORD

nonn,tabf

AUTHOR

Hieronymus Fischer, Jun 21 2007

STATUS

approved

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

Content is available under The OEIS End-User License Agreement .

Last modified April 16 14:51 EDT 2014. Contains 240600 sequences.