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A211013 Second 13-gonal numbers: a(n) = n*(11*n+9)/2. 6
0, 10, 31, 63, 106, 160, 225, 301, 388, 486, 595, 715, 846, 988, 1141, 1305, 1480, 1666, 1863, 2071, 2290, 2520, 2761, 3013, 3276, 3550, 3835, 4131, 4438, 4756, 5085, 5425, 5776, 6138, 6511, 6895, 7290, 7696, 8113, 8541, 8980, 9430, 9891, 10363 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

Sequence found by reading the line from 0, in the direction 0, 31... and the line from 10, in the direction 10, 63,..., in the square spiral whose vertices are the generalized 13-gonal numbers A195313.

LINKS

Table of n, a(n) for n=0..43.

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

FORMULA

G.f.: x(10+x)/(1-x)^3. - Philippe Deléham, Mar 27 2013

a(n) = 3*a(n-1) - 3*a(n-2) + a(n-3) with a(0) = 0, a(1) = 10, a(2) = 31. - Philippe Deléham, Mar 27 2013

a(n) = A051865(n) + 9n = A180223(n) + 8n = A022268(n) + 5n = A022269(n) + 4n = A152740(n) - n. - Philippe Deléham, Mar 27 2013

a(n) = A218530(11n+9). - Philippe Deléham, Mar 27 2013

PROG

(PARI) a(n)=n*(11*n+9)/2 \\ Charles R Greathouse IV, Jun 17 2017

CROSSREFS

Bisection of A195313.

Second k-gonal numbers (k=5..14): A005449, A014105, A147875, A045944, A179986, A033954, A062728, A135705, this sequence, A211014.

Cf. A051865.

Sequence in context: A063154 A100500 A209994 * A085473 A051943 A059306

Adjacent sequences:  A211010 A211011 A211012 * A211014 A211015 A211016

KEYWORD

nonn,easy

AUTHOR

Omar E. Pol, Aug 04 2012

STATUS

approved

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Last modified November 20 06:06 EST 2018. Contains 317385 sequences. (Running on oeis4.)