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 A332159 a(n) = 5*(10^(2*n+1)-1)/9 + 4*10^n. 9
 9, 595, 55955, 5559555, 555595555, 55555955555, 5555559555555, 555555595555555, 55555555955555555, 5555555559555555555, 555555555595555555555, 55555555555955555555555, 5555555555559555555555555, 555555555555595555555555555, 55555555555555955555555555555, 5555555555555559555555555555555 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,1 LINKS Table of n, a(n) for n=0..15. Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000). FORMULA a(n) = 5*A138148(n) + 9*10^n = A002279(2n+1) + 4*10^n. G.f.: (9 - 404*x - 100*x^2)/((1 - x)(1 - 10*x)(1 - 100*x)). a(n) = 111*a(n-1) - 1110*a(n-2) + 1000*a(n-3) for n > 2. MAPLE A332159 := n -> 5*(10^(2*n+1)-1)/9+4*10^n; MATHEMATICA Array[5 (10^(2 # + 1)-1)/9 + 4*10^# &, 15, 0] Table[FromDigits[Join[PadRight[{}, n, 5], PadRight[{9}, n+1, 5]]], {n, 0, 20}] (* or *) LinearRecurrence[ {111, -1110, 1000}, {9, 595, 55955}, 20] (* Harvey P. Dale, May 31 2023 *) PROG (PARI) apply( {A332159(n)=10^(n*2+1)\9*5+4*10^n}, [0..15]) (Python) def A332159(n): return 10**(n*2+1)//9*5+4*10**n CROSSREFS Cf. A002275 (repunits R_n = (10^n-1)/9), A002279 (5*R_n), A011557 (10^n). Cf. A138148 (cyclops numbers with binary digits), A002113 (palindromes). Cf. A332119 .. A332189 (variants with different repeated digit 1, ..., 8). Cf. A332150 .. A332159 (variants with different middle digit 0, ..., 9). Sequence in context: A061611 A238609 A015092 * A139107 A226552 A277232 Adjacent sequences: A332156 A332157 A332158 * A332160 A332161 A332162 KEYWORD nonn,base,easy AUTHOR M. F. Hasler, Feb 09 2020 STATUS approved

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Last modified May 20 19:00 EDT 2024. Contains 372720 sequences. (Running on oeis4.)