A065570 Numbers k such that the first k ternary digits found in the decimal expansion of Pi form a prime.

264, 274, 322, 751, 3112, 24842, 32731

Offset

1,1

Links

Table of n, a(n) for n=1..7.

Mathematica

p = First[ RealDigits[ Pi, 10, 10^5]]; p = p[[ Select[ Range[10^5], p[[ # ]] == 0 || p[[ # ]] == 1 || p[[ # ]] == 2 & ]]]; Do[ If[ PrimeQ[ FromDigits[ Take[p, n], 3]], Print[n]], {n, 1, 4000} ]
Module[{nn=30000, pd}, pd=Select[RealDigits[Pi, 10, nn][[1]], #<3&]; Select[ Range[ Length[pd]], PrimeQ[FromDigits[Take[pd, #], 3]]&]] (* The program generates the first five terms of the sequence. To generate more, increase the constant for "nn, " but it will take a long time to run and the value of nn may be to be 150, 000 or more. *) (* Harvey P. Dale, Jul 31 2020 *)

Crossrefs

Cf. A065832.

Sequence in context: A229480 A266036 A157828 * A345586 A345844 A253694

Adjacent sequences: A065567 A065568 A065569 * A065571 A065572 A065573

Keyword

nonn,base

Author

Robert G. Wilson v, Nov 30 2001

Extensions

a(6)-a(7) from Chai Wah Wu, Apr 07 2020

Status

approved