A209876 a(n) = 36*n - 6.

30, 66, 102, 138, 174, 210, 246, 282, 318, 354, 390, 426, 462, 498, 534, 570, 606, 642, 678, 714, 750, 786, 822, 858, 894, 930, 966, 1002, 1038, 1074, 1110, 1146, 1182, 1218, 1254, 1290, 1326, 1362, 1398, 1434, 1470, 1506, 1542, 1578, 1614, 1650, 1686, 1722, 1758, 1794, 1830, 1866, 1902, 1938, 1974

Offset

1,1

Comments

It appears that the sum of divisors of each term is a multiple of 36. For example, the divisors of a(3) = 102 are {1, 2, 3, 6, 17, 34, 51, 102}, with sum 216 = 6*36.

It also appears that the sum of divisors of each term of {K*n-6} is a multiple of K for K = 72, 144, and 288.

Links

Table of n, a(n) for n=1..55.

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

Formula

G.f.: 6*(x+5)/(x-1)^2 - Harvey P. Dale, Jun 18 2021

From Elmo R. Oliveira, Apr 04 2025: (Start)

E.g.f.: 6*(exp(x)*(6*x - 1) + 1).

a(n) = 6*A016969(n-1).

a(n) = 2*a(n-1) - a(n-2) for n > 2. (End)

Mathematica

36*Range[60]-6 (* or *) LinearRecurrence[{2, -1}, {30, 66}, 60] (* Harvey P. Dale, Jun 18 2021 *)

Crossrefs

Cf. A016969, A183010.

Sequence in context: A175259 A044132 A044513 * A290145 A157346 A219543

Adjacent sequences: A209873 A209874 A209875 * A209877 A209878 A209879

Keyword

nonn,easy

Author

John W. Layman, Mar 14 2012

Status

approved