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A309827
a(n) is the square of the number consisting of one 1 and n 6's: (166...6)^2.
2
1, 256, 27556, 2775556, 277755556, 27777555556, 2777775555556, 277777755555556, 27777777555555556, 2777777775555555556, 277777777755555555556, 27777777777555555555556, 2777777777775555555555556, 277777777777755555555555556, 27777777777777555555555555556
OFFSET
0,2
COMMENTS
All terms are zeroless (element of A052382).
FORMULA
a(n) = A246057(n)^2 = ((5*10^n-2)/3)^2.
a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3).
G.f.: (1+145*x+250*x^2)/((1-x)*(1-10*x)*(1-100*x)).
MATHEMATICA
LinearRecurrence[{111, -1110, 1000}, {1, 256, 27556}, 20] (* Harvey P. Dale, Dec 13 2021 *)
PROG
(PARI) {a(n) = ((5*10^n-2)/3)^2}
(PARI) N=20; x='x+O('x^N); Vec((1+145*x+250*x^2)/((1-x)*(1-10*x)*(1-100*x)))
CROSSREFS
((k*10^n+3-k)/3)^2: A102807 (k=1), A109344 (k=2), A098608 (k=3), A309907 (k=4), this sequence (k=5).
Sequence in context: A206055 A237134 A205948 * A205019 A017212 A181243
KEYWORD
nonn,base
AUTHOR
Seiichi Manyama, Aug 23 2019
STATUS
approved