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A215145 a(n) = 20*n + 1. 3
1, 21, 41, 61, 81, 101, 121, 141, 161, 181, 201, 221, 241, 261, 281, 301, 321, 341, 361, 381, 401, 421, 441, 461, 481, 501, 521, 541, 561, 581, 601, 621, 641, 661, 681, 701, 721, 741, 761, 781, 801, 821, 841, 861, 881, 901, 921, 941, 961, 981 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

Jeremy Gardiner, Table of n, a(n) for n = 0..999

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

FORMULA

From G. C. Greubel, Apr 19 2018: (Start)

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

G.f.: (1+19*x)/(1-x)^2.

E.g.f.: (20*x + 1)*exp(x). (end)

MATHEMATICA

Range[1, 1000, 20]

LinearRecurrence[{2, -1}, {1, 21}, 50] (* G. C. Greubel, Apr 19 2018 *)

PROG

(PARI) for(n=0, 50, print1(20*n + 1, ", ")) \\ G. C. Greubel, Apr 19 2018

(MAGMA) I:=[1, 21]; [n le 2 select I[n] else 2*Self(n-1) - Self(n-2): n in [1..30]]; // G. C. Greubel, Apr 19 2018

CROSSREFS

Cf. A124204.

Sequence in context: A320775 A104393 A261522 * A154576 A173960 A147273

Adjacent sequences:  A215142 A215143 A215144 * A215146 A215147 A215148

KEYWORD

nonn,easy

AUTHOR

Jeremy Gardiner, Aug 04 2012

STATUS

approved

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Last modified November 12 04:21 EST 2019. Contains 329051 sequences. (Running on oeis4.)