A121267 - OEIS

A121267

Number of decimal digits in A047777(n).

1, 5, 1, 3, 1, 2, 1, 4, 3057, 2, 3, 14650, 4, 2, 46, 4

(list; graph; refs; listen; history; text; internal format)

OFFSET

1,2

COMMENTS

Not equal to the first differences of A053013 (which is based on a different variant of A047777).

"A new visitor to an old problem! Jens Kruse Andersen confirmed the primality of Nash's 3057-digit prime using PRIMO." - Carlos Rivera, Sep 2002

If it exists, then a(17) > 50000. - Lucas A. Brown, Jul 04 2024

LINKS

Table of n, a(n) for n=1..16.

Lucas A. Brown, Python program.

Carlos Rivera, Problem 18. Pi as a concatenation of the smallest contiguous different primes, The Prime Puzzles & Problems Connection.

PROG

(PARI) default(realprecision, 5000); c=Pi/10; u=[]; for(k=1, 9e9, ispseudoprime(c\.1^k) & !setsearch(u, c\.1^k) & (u=setunion(u, Set(c\.1^k))) & !print1(k, ", ") & k=0*c=frac(c*10^k)) \\ M. F. Hasler, Sep 15 2013

CROSSREFS

Cf. A047777, A053013.

Sequence in context: A134568 A198798 A229181 * A111740 A327921 A155059

Adjacent sequences: A121264 A121265 A121266 * A121268 A121269 A121270

KEYWORD

nonn,base,more,hard

AUTHOR

Robert G. Wilson v, Aug 23 2006

EXTENSIONS

The old values a(10) onwards were incorrect, as discovered by M. F. Hasler, Aug 31 2013. The old values, the b-file and the Mathematica program have been deleted. - N. J. A. Sloane, Sep 01 2013

STATUS

approved