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A115565 a(n) = 5*n^4 - 10*n^3 + 20*n^2 - 15*n + 11. 1
11, 61, 281, 911, 2311, 4961, 9461, 16531, 27011, 41861, 62161, 89111, 124031, 168361, 223661, 291611, 374011, 472781, 589961, 727711, 888311, 1074161, 1287781, 1531811, 1809011, 2122261, 2474561, 2869031, 3308911, 3797561, 4338461, 4935211, 5591531 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
FORMULA
a(1-n) = a(n) = 5*(n^2-n)^2 +15*(n^2-n) +11. - Michael Somos, May 15 2006
a(1)=11, a(2)=61, a(3)=281, a(4)=911, a(5)=2311, a(n)=5*a(n-1)-10*a(n-2)+ 10*a(n-3)-5*a(n-4)+a(n-5). - Harvey P. Dale, Oct 03 2011
G.f.: x*(11+6*x+86*x^2+6*x^3+11*x^4)/(1-x)^5. - Wesley Ivan Hurt, Aug 22 2015
MAPLE
A115565:=n->5*n^4 - 10*n^3 + 20*n^2 - 15*n + 11: seq(A115565(n), n=1..40); # Wesley Ivan Hurt, Aug 22 2015
MATHEMATICA
Table[5n^4-10n^3+20n^2-15n+11, {n, 40}] (* or *) LinearRecurrence[ {5, -10, 10, -5, 1}, {11, 61, 281, 911, 2311}, 40] (* Harvey P. Dale, Oct 03 2011 *)
CoefficientList[Series[(11 + 6 x + 86 x^2 + 6 x^3 + 11 x^4)/(1 - x)^5, {x, 0, 40}], x] (* Wesley Ivan Hurt, Aug 22 2015 *)
PROG
ay1[1] := 11; a[1] :=50; b[1] :=170; c[1] :=240; k := 120; Repeat ay1[1] := ay1[1] + a[1]; a[1] := a[1] + b[1]; b[1] := b[1] + c[1]; c[1] := c[1] + k; writeln(ay1[1]); Until 1 < 0;
(Magma) [5*(n^2-n)^2 +15*(n^2-n) +11: n in [1..40]]; // Vincenzo Librandi, Oct 04 2011
(PARI) a(n) = 5*n^4 - 10*n^3 + 20*n^2 - 15*n + 11 \\ Charles R Greathouse IV, Aug 22 2015
(PARI) first(m)=vector(m, i, 5*i^4 - 10*i^3 + 20*i^2 - 15*i + 11) \\ Anders Hellström, Aug 22 2015
CROSSREFS
Sequence in context: A023298 A320145 A106992 * A137410 A268863 A199414
KEYWORD
nonn,easy
AUTHOR
Aldrich Stevens (Aldrichstevens(AT)msn.com), Mar 11 2006
EXTENSIONS
Checked by N. J. A. Sloane, Mar 29 2006
Edited by N. J. A. Sloane, Jun 13 2008
STATUS
approved

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Last modified February 28 08:11 EST 2024. Contains 370393 sequences. (Running on oeis4.)