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 A229155 Number of digits of the n-th term of the decimal expansion of e = exp(1) cut into chunks of primes. 2
 1, 1, 649, 1, 1, 2, 29, 1, 1, 2, 1, 1, 1, 53, 1872, 3, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 COMMENTS Trying to cut the decimal expansion A001113 of e=2.718281828... into "prime chunks", one gets (2, 7, p, 5, 3, 11, q, 7, 3, 61, 3, 3, 2, r, ...) where p, q, r are 649-, 29-, 53-digit primes, respectively. The size of p makes it impossible to register this more fundamental sequence in the OEIS as it is done in A047777 for Pi. This led us to store just the length of the terms in this sequence. Sequence A121267 is a (not exact) analog for Pi; note that A047777 requires all primes to be distinct, while we allow repetition of 7, 3, 2, ... as seen in the above example. If we did not, the terms following 29 would be 2, 2, 6, 3, 7, 8, 3, 441, 9, 17, ... instead of 1, 1, 2, 1, 1, 1, 53, ... LINKS Table of n, a(n) for n=1..17. Joseph L. Pe, Trying to Write e as a Concatenation of Primes (2009) PROG (PARI) default(realprecision, 2000); c=exp(1)/10; for(k=1, 9e9, ispseudoprime(c\.1^k) & !print1(k, ", ") & k=0*c=frac(c*10^k)) CROSSREFS Cf. A007512, A001113, A047658, A064118. Sequence in context: A035755 A107551 A202056 * A154358 A252538 A185666 Adjacent sequences: A229152 A229153 A229154 * A229156 A229157 A229158 KEYWORD nonn,base,more AUTHOR M. F. Hasler, Sep 15 2013 EXTENSIONS a(15)-a(17) from Jinyuan Wang, Mar 26 2020 STATUS approved

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Last modified July 17 04:55 EDT 2024. Contains 374360 sequences. (Running on oeis4.)