A332152 - OEIS

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A332152

a(n) = 5*(10^(2*n+1)-1)/9 - 3*10^n.

2, 525, 55255, 5552555, 555525555, 55555255555, 5555552555555, 555555525555555, 55555555255555555, 5555555552555555555, 555555555525555555555, 55555555555255555555555, 5555555555552555555555555, 555555555555525555555555555, 55555555555555255555555555555, 5555555555555552555555555555555

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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) + 2*10^n = A002279(2n+1) - 3*10^n.

G.f.: (2 + 303*x - 800*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

A332152 := n -> 5*(10^(2*n+1)-1)/9-3*10^n;

MATHEMATICA

Array[5 (10^(2 # + 1)-1)/9 - 3*10^# &, 15, 0]

PROG

(PARI) apply( {A332152(n)=10^(n*2+1)\9*5-3*10^n}, [0..15])

(Python) def A332152(n): return 10**(n*2+1)//9*5-3*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. A332112 .. A332192 (variants with different repeated digit 1, ..., 9).

Cf. A332150 .. A332159 (variants with different middle digit 0, ..., 9).

Sequence in context: A283756 A352803 A071613 * A262649 A202277 A177836

Adjacent sequences: A332149 A332150 A332151 * A332153 A332154 A332155

KEYWORD

nonn,base,easy

AUTHOR

M. F. Hasler, Feb 09 2020

STATUS

approved