

A201545


Numbers n such that the nth digit (after the decimal point) in the decimal expansion of Pi are the occurrence of the least significant digit represented by the more significant digits


0



47, 281, 381, 399, 515, 648, 918, 928, 1303, 1538, 3746
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OFFSET

1,1


COMMENTS

The 47th digit after the decimal point in the expansion of Pi (A000796, but without the leading 3) is the 4th occurrence of the digit 7; the 281st is the 28th occurrence of the digit 1; etc.
Only individual least significant digits are included. Does not include, for example, 467, which is the beginning position of the 4th occurrence of 67.


LINKS

Table of n, a(n) for n=1..11.
Dave Andersen, PiSearch Page


EXAMPLE

The 399th digit after the decimal point in Pi is the 39th occurrence of the digit 9.
225 is not in the sequence, as the 225th digit is 5, but this is the 23rd occurrence of the digit 5 in the expansion of pi, not the 22nd.


MAPLE

Digits := 4000 ;
pdg := proc(n)
floor(Pi*10^n) mod 10 ;
end proc:
dfreq := Vector(10, 0) ;
for n from 1 do
d := pdg(n) ;
dfreq[d+1] := dfreq[d+1]+1 ;
ld := n mod 10 ;
hid := floor(n/10) ;
if dfreq[d+1] = hid and ld = d then
print(n);
end if;
end do: # R. J. Mathar, Dec 16 2011


CROSSREFS

Cf. A000796, A057680.
Sequence in context: A142119 A231440 A142164 * A142774 A069760 A140043
Adjacent sequences: A201542 A201543 A201544 * A201546 A201547 A201548


KEYWORD

nonn,base


AUTHOR

Matthew Goers, Dec 02 2011


STATUS

approved



