The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A332174 (Bold, blue-underlined text is an addition; faded, red-underlined text is a ~~deletion~~.)
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A332174

a(n) = 7*(10^(2n+1)-1)/9 - 3*10^n.
(history; published version)

#12 by M. F. Hasler at Tue Feb 11 08:26:38 EST 2020

STATUS

editing

approved

#11 by M. F. Hasler at Tue Feb 11 08:26:17 EST 2020

MATHEMATICA

Array[7 (10^(2 # + 1) - 1)/9 - 3*10^# &, 15, 0]

STATUS

approved

editing

#10 by M. F. Hasler at Sat Feb 08 18:05:39 EST 2020

STATUS

editing

approved

#9 by M. F. Hasler at Sat Feb 08 18:05:17 EST 2020

PROG

(Python) def A332174(n): return 10**(n*2+1)//9*7-3*10^n

CROSSREFS

Cf. A002275 (repunits R_n = (10^n-1)/9), A002281 (7*R_n), A011557 (10^n).

STATUS

approved

editing

#8 by M. F. Hasler at Sat Feb 08 17:28:31 EST 2020

STATUS

editing

approved

#7 by M. F. Hasler at Sat Feb 08 17:28:14 EST 2020

CROSSREFS

Cf. A332171 .. A332179 (variants with different middle digit 1, ..., 9).

#6 by M. F. Hasler at Sat Feb 08 14:49:11 EST 2020

FORMULA

G.f.: (1 4 + 404303*x - 11001000*x^2)/((1 - x)*(1 - 10*x)*(1 - 100*x)).

MAPLE

A332173 A332174 := n -> 7*(10^(n*2+1)-1)/9 - 3*10^n;

STATUS

proposed

editing

#5 by Stefano Spezia at Sat Feb 08 14:47:11 EST 2020

STATUS

editing

proposed

#4 by Stefano Spezia at Sat Feb 08 14:47:05 EST 2020

FORMULA

E.g.f.: (1/9)*exp(x)*(70*exp(99*x) - 27*exp(9*x) - 7). - Stefano Spezia, Feb 08 2020

STATUS

proposed

editing

#3 by M. F. Hasler at Sat Feb 08 14:43:23 EST 2020

STATUS

editing

proposed