A182455 a(0)=1, a(n) = (a(n-1) mod (n+2))*(n+2).

1, 3, 12, 10, 24, 21, 40, 36, 60, 55, 84, 78, 112, 105, 144, 136, 180, 171, 220, 210, 264, 253, 312, 300, 364, 351, 420, 406, 480, 465, 544, 528, 612, 595, 684, 666, 760, 741, 840, 820, 924, 903, 1012, 990, 1104, 1081, 1200, 1176, 1300, 1275, 1404, 1378, 1512, 1485

Offset

0,2

Links

Reinhard Zumkeller, Table of n, a(n) for n = 0..10000

Index entries for linear recurrences with constant coefficients, signature (1,2,-2,-1,1).

Formula

a(0)=1, a(n) = (a(n-1) mod (n+2))*(n+2).

For k>0, a(2*k)=(k+1)*(2*k+4), a(2*k+1)=(k+1)*(2*k+3).

G.f.: (1 + 2*x + 7*x^2 - 6*x^3 - 3*x^4 + 3*x^5)/((1 - x)^3*(1 + x)^2). - Andrew Howroyd, Oct 27 2025

Example

a(5) = (a(4) mod 7)*7 = (24 mod 7)*7 = 3*7 = 21.

Prog

(Python)
a=1
for n in range(1, 55):
    print(a, end=', ')
    a = (a%(n+2)) * (n+2)
(Haskell)
a182455 n = a182455_list !! n
a182455_list = 1 : zipWith (*) (zipWith mod a182455_list [3..]) [3..]
-- Reinhard Zumkeller, May 01 2012

Crossrefs

Cf. A093005 (a(n)=(a(n-1) mod (n+1))*(n+1)).

Sequence in context: A038230 A292581 A207852 * A110345 A018999 A380057

Adjacent sequences: A182452 A182453 A182454 * A182456 A182457 A182458

Keyword

nonn,easy

Author

Alex Ratushnyak, Apr 30 2012

Status

approved