A053741 Sum of even numbers in range 10*n to 10*n+9.

20, 70, 120, 170, 220, 270, 320, 370, 420, 470, 520, 570, 620, 670, 720, 770, 820, 870, 920, 970, 1020, 1070, 1120, 1170, 1220, 1270, 1320, 1370, 1420, 1470, 1520, 1570, 1620, 1670, 1720, 1770, 1820, 1870, 1920, 1970, 2020, 2070, 2120, 2170, 2220, 2270

Offset: 0

Author

Odimar Fabeny, Feb 13 2000

Keywords

• nonn
• easy

Examples

			20 is sum of 0, 2, 4, 6, 8;
70 is sum of 10, 12, 14, 16, 18;
120 is sum of 20, 22, 24, 26, 28; etc.
		

Links

• Vincenzo Librandi, Table of n, a(n) for n = 0..10000
• Tanya Khovanova, Recursive Sequences
• Index entries for linear recurrences with constant coefficients, signature (2,-1).

Crossrefs

Cf. A053742, A053743.

Programs

GAP

List([0..50], n-> 10*(2+5*n)); # G. C. Greubel, Sep 06 2019

Magma

[20+50*n: n in [0..50]]; // Vincenzo Librandi, Aug 12 2011

Maple

seq(10*(2+5*n), n=0..50); # G. C. Greubel, Sep 06 2019

Mathematica

50Range[50]-30  (* Harvey P. Dale, Mar 06 2011 *)

PARI

vector(50, n, 10*(5*n-3)) \\ G. C. Greubel, Sep 06 2019

Sage

[10*(2+5*n) for n in (0..50)] # G. C. Greubel, Sep 06 2019

Formula

a(n) = 50*n + 20.

From Colin Barker, Jun 27 2012: (Start)

a(n) = 2*a(n-1) - a(n-2).

G.f.: 10*(2+3*x)/(1-x)^2. (End)

E.g.f.: 10*(2+5*x)*exp(x). - G. C. Greubel, Sep 06 2019

Extensions

More terms from James Sellers, Feb 22 2000