A202475 - OEIS

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A202475

Decimal expansion of the real number x between 3 and 4 where 2^x = x!.

3, 4, 5, 9, 8, 6, 5, 6, 4, 4, 0, 4, 4, 9, 9, 9, 1, 3, 4, 1, 8, 7, 8, 6, 1, 0, 8, 1, 0, 6, 8, 9, 8, 1, 2, 0, 2, 7, 7, 5, 1, 8, 4, 5, 9, 9, 0, 6, 4, 2, 8, 3, 1, 4, 5, 2, 9, 8, 0, 6, 8, 8, 7, 2, 8, 5, 8, 2, 5, 2, 2, 1, 2, 1, 1, 1, 4, 5, 1, 3, 1, 3, 8, 9, 7, 9, 2

(list; constant; graph; refs; listen; history; text; internal format)

OFFSET

1,1

COMMENTS

2^3 > 3! but 2^4 < 4!. Since the exponential and generalized factorial (Gamma) functions are continuous, it follows that 2^x = x! ( = gamma(x+1) ) for some x between 3 and 4. It's about 3.45986564404500.

LINKS

Table of n, a(n) for n=1..87.

WolframAlpha, Find value

EXAMPLE

3.459865644044999134187861081068981202775184599...

MATHEMATICA

RealDigits[x/.FindRoot[2^x==x!, {x, 3, 4}, WorkingPrecision->120]][[1]] (* Harvey P. Dale, Jan 22 2016 *)

PROG

(PARI) solve(x=3, 4, 2^x-gamma(x+1)) \\ Michel Marcus, Aug 03 2013

CROSSREFS

Sequence in context: A342772 A065336 A079097 * A036710 A098801 A259615

Adjacent sequences: A202472 A202473 A202474 * A202476 A202477 A202478