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A317547 Decimal expansion of f(0) such that f(n)=log(abs(f(n-1))) > 0 iff n is a prime number (negated). 0
2, 1, 7, 2, 2, 6, 8, 9, 8, 3, 5, 6, 1, 2, 0, 8, 4, 2, 7, 4, 3, 0, 1, 9, 2, 8, 8, 2, 3, 3, 3, 5, 3, 8, 8, 8, 5, 4, 1, 4, 4, 1, 0, 2, 2, 3, 3, 0, 0, 6, 1, 7, 3, 6, 2, 2, 9, 6, 9, 4, 2, 0, 1, 4, 9, 3, 8, 4, 4, 9, 9, 7, 7, 8, 5, 1, 9, 2, 9, 7, 1, 1, 9, 3, 5, 5, 0, 3, 2, 2, 2, 0, 5, 9, 0, 8, 5, 8, 8, 8 (list; constant; graph; refs; listen; history; text; internal format)
OFFSET

-1,1

COMMENTS

If f(0)=A201942, f(n) will generate the odd numbers.

LINKS

Table of n, a(n) for n=-1..98.

J. Maiga, Fun with signed nested exponentials and the prime numbers

FORMULA

Equals lim_{n->oo} sf(0)*exp(sf(1)*exp(...sf(n-1)*exp(sf(n)))) where sf(n)=2*(A010051(n)-1).

EXAMPLE

-0.02172268983561208427430192882333538885414410223300617362296942014938449977851...

MATHEMATICA

f0[n_] := (v = 0; For[i = n, i >= 0, i--, v = If[PrimeQ[i], 1, -1]*Exp[v]]; v);

RealDigits[f0[1000], 10, 100][[1]]

CROSSREFS

Cf. A010051, A201942.

Sequence in context: A124392 A144446 A121416 * A089329 A213053 A200236

Adjacent sequences:  A317544 A317545 A317546 * A317548 A317549 A317550

KEYWORD

nonn,cons

AUTHOR

Jon Maiga, Jul 30 2018

STATUS

approved

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Last modified November 16 00:11 EST 2018. Contains 317252 sequences. (Running on oeis4.)