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

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A195314 Centered 28-gonal numbers. 6
1, 29, 85, 169, 281, 421, 589, 785, 1009, 1261, 1541, 1849, 2185, 2549, 2941, 3361, 3809, 4285, 4789, 5321, 5881, 6469, 7085, 7729, 8401, 9101, 9829, 10585, 11369, 12181, 13021, 13889, 14785, 15709, 16661, 17641, 18649, 19685, 20749, 21841, 22961, 24109 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Sequence found by reading the line from 1, in the direction 1, 29,..., in the square spiral whose vertices are the generalized enneagonal numbers A118277. Semi-axis opposite to A144555 in the same spiral.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..10000

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

FORMULA

a(n) = 14*n^2 - 14*n + 1.

G.f. -x*(1+26*x+x^2) / (x-1)^3 . - R. J. Mathar, Sep 18 2011

a(1)=1, a(2)=29, a(3)=85, a(n)=3*a(n-1)-3*a(n-2)+a(n-3) [From Harvey P. Dale, Oct 01 2011]

MATHEMATICA

Table[14n^2-14n+1, {n, 50}] (* or *) LinearRecurrence[{3, -3, 1}, {1, 29, 85}, 50]

PROG

(MAGMA) [(14*n^2-14*n+1): n in [1..50]]; // Vincenzo Librandi, Sep 19 2011

(PARI) a(n)=14*n^2-14*n+1 \\ Charles R Greathouse IV, Oct 07 2015

CROSSREFS

Bisection of A195145.

Cf. A003154, A069129, A069133, A069190, A195315, A195316, A195317, A195318.

Sequence in context: A142592 A255187 A273362 * A124784 A126383 A032508

Adjacent sequences:  A195311 A195312 A195313 * A195315 A195316 A195317

KEYWORD

nonn,easy

AUTHOR

Omar E. Pol, Sep 16 2011

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 November 12 19:19 EST 2018. Contains 317116 sequences. (Running on oeis4.)