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 A064489 Let p = prime(n); a(n) = smallest m such that prime(m) has p digits. 2
 5, 26, 1230, 78499, 455052512, 37607912019, 279238341033926, 24739954287740861, 201467286689315906291 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE n=5; prime(5)=11 and 11 is the first prime with a prime number of decimal digits. PROG (PARI) l(n)=ln=0; while(n, n=floor(n/10); ln++); return(ln); a=0; for(n=1, 10^6, x=l(prime(n)); if(isprime(x), b=x; if(b>a, a=b; print(n)))) (Python) from sympy import prime, nextprime, primepi def a(n): return primepi(nextprime(10**(prime(n)-1))) print([a(n) for n in range(1, 6)]) # Michael S. Branicky, May 26 2021 CROSSREFS Cf. A064490. a(n) = 1 + A006880(A000040(n-1)). Sequence in context: A226125 A132509 A281747 * A081089 A180928 A342998 Adjacent sequences: A064486 A064487 A064488 * A064490 A064491 A064492 KEYWORD base,easy,nonn AUTHOR Jason Earls, Oct 04 2001 EXTENSIONS More terms from David Wasserman, Jul 22 2002 STATUS approved

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Last modified January 29 00:02 EST 2023. Contains 359905 sequences. (Running on oeis4.)