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A053741 Sum of even numbers in range 10n to 10n+9. 3
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,1

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).

FORMULA

a(n) = 50*n+20.

a(n) = 2*a(n-1)-a(n-2). G.f.: 10*(2+3*x)/(1-x)^2. [Colin Barker, Jun 27 2012]

EXAMPLE

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.

MATHEMATICA

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

PROG

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

CROSSREFS

Cf. A053742, A053743.

Sequence in context: A234367 A071395 A245856 * A052516 A083873 A240820

Adjacent sequences:  A053738 A053739 A053740 * A053742 A053743 A053744

KEYWORD

nonn,easy

AUTHOR

Odimar Fabeny, Feb 13 2000

EXTENSIONS

More terms from James A. Sellers, Feb 22 2000

STATUS

approved

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Last modified May 30 06:51 EDT 2017. Contains 287302 sequences.