A163292 a(n) = n-th prime minus (number of digits of n-th prime written in base 4).
1, 2, 3, 5, 9, 11, 14, 16, 20, 26, 28, 34, 38, 40, 44, 50, 56, 58, 63, 67, 69, 75, 79, 85, 93, 97, 99, 103, 105, 109, 123, 127, 133, 135, 145, 147, 153, 159, 163, 169, 175, 177, 187, 189, 193, 195, 207, 219, 223, 225, 229, 235, 237, 247, 252, 258, 264, 266, 272, 276
Offset: 1
Examples
a(6) = 11 (= 13 - 2); a(7) = 14 (= 17 - 3); ... a(54) = 247 (= 251 - 4); a(55) = 252 (= 257 - 5).
Links
- Harvey P. Dale, Table of n, a(n) for n = 1..1000
Programs
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Maple
A000040 := proc(n) ithprime(n) ; end: A163291 := proc(n) max(1,ilog[4](A000040(n))+1) ; end: A163292 := proc(n) A000040(n)-A163291(n) ; end: seq(A163292(n),n=1..100) ; #R. J. Mathar, Jul 26 2009
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Mathematica
#-IntegerLength[#,4]&/@Prime[Range[60]] (* Harvey P. Dale, Dec 14 2015 *)
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PARI
a(n) = my(p=prime(n)); p - #digits(p, 4); \\ Michel Marcus, Mar 03 2019