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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A171379 Triangle sequence of:t(n,k)=A059481(n,k)*(A059481(n,k)-1)/2 0
0, 1, 3, 3, 15, 45, 6, 45, 190, 595, 10, 105, 595, 2415, 7875, 15, 210, 1540, 7875, 31626, 106491, 21, 378, 3486, 21945, 106491, 426426, 1471470, 28, 630, 7140, 54285, 313236, 1471470, 5887596, 20701395, 36, 990, 13530, 122265, 827541, 4507503 (list; table; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

Row sums are:

{0, 4, 63, 836, 11000, 147757, 2030217, 28435780, 404461170, 5824442504,...}

The sequence is the number of connections between figurate numbers A059481 as points page 25 Riordan.

REFERENCES

J. Riordan, An Introduction to Combinatorial Analysis, Wiley, 1958, p. 25.

LINKS

Table of n, a(n) for n=1..42.

FORMULA

t(n,k)=Binomial[n + k - 1, k]*(Binomial[n + k - 1, k] - 1)/2

EXAMPLE

0;

1, 3;

3, 15, 45;

6, 45, 190, 595;

10, 105, 595, 2415, 7875;

15, 210, 1540, 7875, 31626, 106491;

21, 378, 3486, 21945, 106491, 426426, 1471470;

28, 630, 7140, 54285, 313236, 1471470, 5887596, 20701395;

36, 990, 13530, 122265, 827541, 4507503, 20701395, 82812015, 295475895;

45, 1485, 24090, 255255, 2003001, 12522510, 65431080, 295475895, 1181927890, 4266801253;

MATHEMATICA

t[n_, k_] = Binomial[n + k - 1, k]*(Binomial[n + k - 1, k] - 1)/2

Table[Table[t[n, k], {k, 1, n}], {n, 1, 10}]

Flatten[%]

CROSSREFS

Cf. A059481, A143418.

Sequence in context: A126319 A165553 A056314 * A078631 A160639 A280781

Adjacent sequences:  A171376 A171377 A171378 * A171380 A171381 A171382

KEYWORD

nonn,uned,tabl

AUTHOR

Roger L. Bagula, Dec 07 2009

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 | More pages
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy .

Last modified August 22 22:22 EDT 2017. Contains 290952 sequences.