A139245 a(n) = 20*n - 16.

4, 24, 44, 64, 84, 104, 124, 144, 164, 184, 204, 224, 244, 264, 284, 304, 324, 344, 364, 384, 404, 424, 444, 464, 484, 504, 524, 544, 564, 584, 604, 624, 644, 664, 684, 704, 724, 744, 764, 784, 804, 824, 844, 864, 884, 904, 924, 944, 964, 984, 1004, 1024, 1044

Offset: 1

Author

Odimar Fabeny, Jun 06 2008

Keywords

• easy
• nonn

Comments

Multiples of 4 with the unit digit equal to 4.

Positive integers that are the product of two integers ending with 2 (see A017293). - Stefano Spezia, Jul 25 2021

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..2000
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Subsequence of A034709, together with A017281, A017293, A139222, A017329, A139249, A139264, A139279 and A139280.

Cf. A017293.

Programs

Magma

[20*n-16: n in [1..60]]; // Vincenzo Librandi, Jun 19 2011

Maple

A139245:=n->20*n-16; seq(A139245(n), n=1..100); # Wesley Ivan Hurt, Jan 17 2014

Mathematica

Range[4, 1500, 20] (* Vladimir Joseph Stephan Orlovsky, Jun 01 2011 *)

PARI

a(n)=20*n-16 \\ Charles R Greathouse IV, Aug 25 2014

Formula

a(n) = a(n-1) + 20.

a(n) = 4*A016861(n-1). - Wesley Ivan Hurt, Jan 17 2014

From Stefano Spezia, Jul 25 2021: (Start)

O.g.f.: 4*x*(1 + 4*x)/(1 - x)^2.

E.g.f.: 16 + 4*exp(x)*(5*x - 4).

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

Extensions

More terms from Reinhard Zumkeller, Jun 22 2008