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A140515 Numbers n such that one of floor(10^n * Pi) or ceiling(10^n * Pi) is prime. 1
0, 1, 5, 11, 18, 37, 601, 1901, 2394, 3970, 5826, 16207 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

Table of n, a(n) for n=1..12.

Carlos B. Rivera F. Puzzle 50. Approximation to pi with primes, The Prime Puzzles and Problems Connection.

Eric Weisstein's World of Mathematics, Pi Digits

EXAMPLE

ceiling(10^11*Pi) = ceiling(314159265358.9...) = 314159265359 is prime, so 11 is in the sequence.

PROG

(PARI) isA140515(n)=isprime(bitor(floor(10^n*Pi), 1))

CROSSREFS

Sequence in context: A140697 A048253 A102174 * A056996 A102184 A290751

Adjacent sequences:  A140512 A140513 A140514 * A140516 A140517 A140518

KEYWORD

nonn,base,more

AUTHOR

Marvin Ray Burns, Jul 01 2008, Jul 02 2008

STATUS

approved

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Last modified July 15 00:36 EDT 2020. Contains 335762 sequences. (Running on oeis4.)