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

1,2

Links

Table of n, a(n) for n=1..39.

Index entries for linear recurrences with constant coefficients, signature (0,0,0,0,0,10).

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

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

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 *)

Prog

(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

Crossrefs

Cf. A007770, A000012, A171250.

Sequence in context: A114961 A219045 A199427 * A123834 A064629 A215579

Adjacent sequences: A178505 A178506 A178507 * A178509 A178510 A178511

Keyword

nonn,easy

Author

Paul Curtz, May 29 2010

Extensions

Dissassociated with sums-of-squares sequences by R. J. Mathar, Jun 07 2010

Status

approved