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A332145 a(n) = 4*(10^(2*n+1)-1)/9 + 10^n. 1
5, 454, 44544, 4445444, 444454444, 44444544444, 4444445444444, 444444454444444, 44444444544444444, 4444444445444444444, 444444444454444444444, 44444444444544444444444, 4444444444445444444444444, 444444444444454444444444444, 44444444444444544444444444444, 4444444444444445444444444444444 (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) = 4*A138148(n) + 5*10^n = A002278(2n+1) + 10^n.

G.f.: (5 - 101*x - 300*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

A332145 := n -> 4*(10^(2*n+1)-1)/9+10^n;

MATHEMATICA

Array[4 (10^(2 # + 1)-1)/9 + 10^# &, 15, 0]

PROG

(PARI) apply( {A332145(n)=10^(n*2+1)\9*4+10^n}, [0..15])

(Python) def A332145(n): return 10**(n*2+1)//9*4+10**n

CROSSREFS

Cf. A002275 (repunits R_n = (10^n-1)/9), A002278 (4*R_n), A011557 (10^n).

Cf. A138148 (cyclops numbers with binary digits), A002113 (palindromes).

Cf. A332115 .. A332195 (variants with different repeated digit 1, ..., 9).

Cf. A332140 .. A332149 (variants with different middle digit 0, ..., 9).

Sequence in context: A300971 A300928 A221626 * A144509 A240700 A060855

Adjacent sequences:  A332142 A332143 A332144 * A332146 A332147 A332148

KEYWORD

nonn,base,easy

AUTHOR

M. F. Hasler, Feb 09 2020

STATUS

approved

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Last modified September 26 17:30 EDT 2021. Contains 347670 sequences. (Running on oeis4.)