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Multiples of 5 having only even digits.
2

%I #11 Feb 15 2017 00:14:21

%S 0,20,40,60,80,200,220,240,260,280,400,420,440,460,480,600,620,640,

%T 660,680,800,820,840,860,880,2000,2020,2040,2060,2080,2200,2220,2240,

%U 2260,2280,2400,2420,2440,2460,2480,2600,2620,2640,2660,2680,2800,2820,2840

%N Multiples of 5 having only even digits.

%H Harvey P. Dale, <a href="/A061830/b061830.txt">Table of n, a(n) for n = 0..1000</a>

%H <a href="/index/Ar#10-automatic">Index entries for 10-automatic sequences</a>.

%H <a href="/index/Rec#order_26">Index entries for linear recurrences with constant coefficients</a>, signature (1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, -1).

%F a(0)=0, a(1)=20, a(2)=40, a(3)=60, a(4)=80, a(5)=200, a(6)=220, a(7)=240, a(8)=260, a(9)=280, a(10)=400, a(11)=420, a(12)=440, a(13)=460, a(14)=480, a(15)=600, a(16)=620, a(17)=640, a(18)=660, a(19)=680, a(20)=800, a(21)=820, a(22)=840, a(23)=860, a(24)=880, a(25)=2000, a(n)=a(n-1)+ a(n-25)- a(n-26). - _Harvey P. Dale_, Feb 24 2014

%e 220 = 5*44 is a term having all even digits.

%t Select[5*Range[0,2000],And@@EvenQ[IntegerDigits[#]]&] (* or *) LinearRecurrence[ {1,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,1,-1},{0,20,40,60,80,200,220,240,260,280,400,420,440,460,480,600,620,640,660,680,800,820,840,860,880,2000},50] (* _Harvey P. Dale_, Feb 24 2014 *)

%o (PARI) is(n)=n%10==0 && #setintersect(Set(digits(n)), [1,3,5,7,9])==0 \\ _Charles R Greathouse IV_, Feb 15 2017

%Y Cf. A061829.

%K nonn,base,easy

%O 0,2

%A _Amarnath Murthy_, May 29 2001

%E More terms from Larry Reeves (larryr(AT)acm.org), May 30 2001