login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A062123 a(n) = 2 + 9*n*(1 + n)/2. 10
2, 11, 29, 56, 92, 137, 191, 254, 326, 407, 497, 596, 704, 821, 947, 1082, 1226, 1379, 1541, 1712, 1892, 2081, 2279, 2486, 2702, 2927, 3161, 3404, 3656, 3917, 4187, 4466, 4754, 5051, 5357, 5672, 5996, 6329, 6671, 7022, 7382, 7751, 8129, 8516, 8912, 9317 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

COMMENTS

Third column of A046741.

REFERENCES

I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(2.3.14).

LINKS

Harry J. Smith, Table of n, a(n) for n = 0..1000

Index entries for linear recurrences with constant coefficients, signature (3,-3,1).

FORMULA

G.f.: (1+2*x)*(2+x)/(1-x)^3. Generally, g.f. for k-th column of A046741 is coefficient of y^k in expansion of (1-y)/((1-y-y^2)*(1-y)-(1+y)*x).

a(n) = 9*n + a(n-1), with n>0, a(0)=2. - Vincenzo Librandi, Aug 07 2010

E.g.f.: (4 +18*x +9*x^2)*exp(x)/2. - G. C. Greubel, Jan 31 2019

MATHEMATICA

Table[2 +9*n*(1+n)/2, {n, 0, 50}] (* G. C. Greubel, Jan 31 2019 *)

LinearRecurrence[{3, -3, 1}, {2, 11, 29}, 50] (* Harvey P. Dale, Jan 12 2020 *)

PROG

(PARI) for (n=0, 1000, write("b062123.txt", n, " ", 2 + (n + n^2)*9/2) ) \\ Harry J. Smith, Aug 02 2009

(MAGMA) [2 +9*n*(1+n)/2: n in [0..50]]; // G. C. Greubel, Jan 31 2019

(Sage) [2 +9*n*(1+n)/2 for n in range(50)] # G. C. Greubel, Jan 31 2019

(GAP) List([0..50], n -> 2 +9*n*(1+n)/2); # G. C. Greubel, Jan 31 2019

CROSSREFS

Cf. dumbbells: A002940, A002941, A002889, A046741, A055608, A062124-A062127.

Cf. A235332.

Sequence in context: A090389 A061238 A046500 * A117560 A024178 A009312

Adjacent sequences:  A062120 A062121 A062122 * A062124 A062125 A062126

KEYWORD

nonn,easy

AUTHOR

Vladeta Jovovic, Jun 04 2001

EXTENSIONS

More terms from Larry Reeves (larryr(AT)acm.org), Jun 06 2001

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 April 11 06:00 EDT 2021. Contains 342886 sequences. (Running on oeis4.)