A178508 a(n) = 1, 7, A011557*(period 6: repeat 10, 13, 31, 49, 70, 97).
1, 7, 10, 13, 31, 49, 70, 97, 100, 130, 310, 490, 700, 970, 1000, 1300, 3100, 4900, 7000, 9700, 10000, 13000, 31000, 49000, 70000, 97000, 100000, 130000, 310000, 490000, 700000, 970000, 1000000, 1300000, 3100000, 4900000, 7000000, 9700000, 10000000
Offset: 1
Links
- Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,10).
Programs
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Maple
A178508:=n->10^floor((n-3)/6)*(45+8*cos((n-2)*Pi)+25*cos((n-2)*Pi/3)+19*cos(2*(n-2)*Pi/3)-4*sqrt(3)*(4*sin((n-2)*Pi/3)+sin(2*(n-2)*Pi/3))): 1,7,seq(A178508(n), n=3..50); # Wesley Ivan Hurt, Jun 18 2016
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Mathematica
Join[{1,7},Flatten[Table[10^n {10,13,31,49,70,97},{n,0,6}]]] (* or *) Join[{1,7},LinearRecurrence[{0,0,0,0,0,10},{10,13,31,49,70,97},50]] (* Harvey P. Dale, Nov 19 2013 *) -
PARI
a=[1,7,10,13,31,49,70,97];for(i=1,99,a=concat(a,10*a[#a-5])); a \\ Charles R Greathouse IV, Jun 01 2011
Formula
G.f.: x*(10*x^2+13*x^3+31*x^4+49*x^5+60*x^6+27*x^7+1+7*x)/(1-10*x^6).
a(n) = 10^floor((n-3)/6)*(45+8*cos((n-2)*Pi)+25*cos((n-2)*Pi/3)+19*cos(2*(n-2)*Pi/3)-4*sqrt(3)*(4*sin((n-2)*Pi/3)+sin(2*(n-2)*Pi/3))) for n>2. - Wesley Ivan Hurt, Jun 18 2016
Extensions
Dissassociated with sums-of-squares sequences by R. J. Mathar, Jun 07 2010