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

 

Logo

The OEIS Foundation is grateful to everyone who made a donation during our Annual Appeal.     Visit the new and spectacular Pictures from the OEIS page!

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.

License Agreements, Terms of Use, Privacy Policy .

Last modified February 11 07:59 EST 2016. Contains 268161 sequences.