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A177112
4*(10^n-7).
0
12, 372, 3972, 39972, 399972, 3999972, 39999972, 399999972, 3999999972, 39999999972, 399999999972, 3999999999972, 39999999999972, 399999999999972, 3999999999999972, 39999999999999972, 399999999999999972
OFFSET
1,1
FORMULA
G.f. 12*x*(1+20*x) / ( (10*x-1)*(x-1) ). - R. J. Mathar, Aug 24 2011
a(n) = 12 *A033175(n-1). - R. J. Mathar, Aug 24 2011
MATHEMATICA
4(10^Range[20]-7) (* or *) LinearRecurrence[{11, -10}, {12, 372}, 20] (* Harvey P. Dale, Nov 22 2019 *)
CROSSREFS
Sequence in context: A268550 A235685 A024298 * A081021 A269609 A251590
KEYWORD
nonn,easy
STATUS
approved