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A045803 3-ish numbers (end in 17, 19, 31, 33). 1
17, 19, 31, 33, 117, 119, 131, 133, 217, 219, 231, 233, 317, 319, 331, 333, 417, 419, 431, 433, 517, 519, 531, 533, 617, 619, 631, 633, 717, 719, 731, 733, 817, 819, 831, 833, 917, 919, 931, 933, 1017, 1019, 1031, 1033, 1117, 1119, 1131, 1133, 1217, 1219 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

Index entries for linear recurrences with constant coefficients, signature (1,0,0,1,-1).

FORMULA

G.f.: x*(17+2*x+12*x^2+2*x^3+67*x^4)/(1-x-x^4+x^5). - Colin Barker, Jan 23 2012

a(n) = -75/2 - (23*(-1)^n)/2 - (9-9*i)*(-i)^n - (9+9*i)*i^n + 25*n where i=sqrt(-1). - Colin Barker, Oct 16 2015

MATHEMATICA

Select[Range[1300], MemberQ[{17, 19, 31, 33}, Mod[#, 100]]&] (* or *) LinearRecurrence[{1, 0, 0, 1, -1}, {17, 19, 31, 33, 117}, 50] (* Harvey P. Dale, Dec 17 2014 *)

PROG

(Haskell)

import Data.List (findIndices)

a045803 n = a045803_list !! (n-1)

a045803_list = findIndices (`elem` [17, 19, 31, 33]) $ cycle [0..99]

-- Reinhard Zumkeller, Jan 23 2012

(PARI) a(n) = -75/2 - (23*(-1)^n)/2 - (9-9*I)*(-I)^n - (9+9*I)*I^n + 25*n \\ Colin Barker, Oct 16 2015

(PARI) Vec(x*(17+2*x+12*x^2+2*x^3+67*x^4)/(1-x-x^4+x^5) + O(x^100)) \\ Colin Barker, Oct 16 2015

CROSSREFS

Cf. A045800-A045809.

Cf. A045572, A045797, A045798.

Sequence in context: A155089 A101396 A050266 * A098933 A145485 A290634

Adjacent sequences:  A045800 A045801 A045802 * A045804 A045805 A045806

KEYWORD

nonn,base,easy

AUTHOR

J. H. Conway

EXTENSIONS

More terms from Erich Friedman

STATUS

approved

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Last modified March 25 12:50 EDT 2019. Contains 321470 sequences. (Running on oeis4.)