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 A163291 Number of digits of n-th prime written in base 4. 2
 1, 1, 2, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,3 LINKS G. C. Greubel, Table of n, a(n) for n = 1..1000 FORMULA a(n) = log_4 n + log_4 log n + O(1). - Charles R Greathouse IV, Mar 25 2010 EXAMPLE 6th prime = 13 = 31_4, so a(6) = 2; 7th prime = 17 = 101_4, so a(7) = 3; 54th prime = 251 = 3323_4, so a(54) = 4; 55th prime = 257 = 10001_4, so a(55) = 5. MATHEMATICA IntegerLength[#, 4] & /@ Prime[Range[100]] (* G. C. Greubel, Dec 17 2016 *) PROG (PARI) a(n) = #digits(prime(n), 4); \\ Michel Marcus, Dec 18 2016 CROSSREFS Cf. A004678, A035100. Sequence in context: A092139 A084558 A320065 * A156875 A066339 A345379 Adjacent sequences:  A163288 A163289 A163290 * A163292 A163293 A163294 KEYWORD nonn,base AUTHOR Juri-Stepan Gerasimov, Jul 24 2009 STATUS approved

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Last modified June 20 06:23 EDT 2021. Contains 345157 sequences. (Running on oeis4.)