A364845 - OEIS

A364845

a(n) is the denominator of the fraction h/k with h and k coprime palindrome positive integers at which abs(h/k-Pi) is minimal, with the numerator h of n digits.

1, 7, 151, 494, 11511, 93039, 2332332, 9966699

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OFFSET

1,2

COMMENTS

a(2) = 7 corresponds to the denominator of A068028.

LINKS

Table of n, a(n) for n=1..8.

Index entries for sequences related to the number Pi

EXAMPLE

n fraction approximated value

- ------------------- ------------------

1 3 3

2 22/7 3.1428571428571...

3 474/151 3.1390728476821...

4 1551/494 3.1396761133603...

5 36163/11511 3.1416036834332...

6 292292/93039 3.1416072829673...

7 7327237/2332332 3.1415926206046...

8 31311313/9966699 3.1415931192464...

...

MATHEMATICA

nmax = 8; a = {1}; hmin = kmin = 0; For[n = 2, n <= nmax, n++, minim = Infinity; h = Select[Range[10^(n - 1), 10^n - 1], PalindromeQ]; k = Select[Range[10^(n - 2), 10^n - 1], PalindromeQ]; lh = Length[h]; lk = Length[k]; For[i = 1, i <= lh, i++, For[j = 1, j <= lk, j++, If[(dist = Abs[Part[h, i]/Part[k, j] - Pi]) < minim && GCD[Part[h, i], Part[k, j]] == 1, minim = dist; kmin = Part[k, j]]]]; AppendTo[a, kmin]]; a

CROSSREFS

Cf. A000796, A002113, A068028, A070252, A364844 (numerator), A364846.

Cf. A355622, A355623.

Sequence in context: A070248 A329010 A309855 * A339582 A232446 A362491

Adjacent sequences: A364842 A364843 A364844 * A364846 A364847 A364848

KEYWORD

nonn,base,frac,more

AUTHOR

Stefano Spezia, Aug 10 2023

STATUS

approved