A163292 - OEIS

%I #15 Mar 05 2019 02:17:20

%S 1,2,3,5,9,11,14,16,20,26,28,34,38,40,44,50,56,58,63,67,69,75,79,85,

%T 93,97,99,103,105,109,123,127,133,135,145,147,153,159,163,169,175,177,

%U 187,189,193,195,207,219,223,225,229,235,237,247,252,258,264,266,272,276

%N a(n) = n-th prime minus (number of digits of n-th prime written in base 4).

%H Harvey P. Dale, <a href="/A163292/b163292.txt">Table of n, a(n) for n = 1..1000</a>

%F a(n) = A000040(n) - A163291(n).

%e a(6) = 11 (= 13 - 2);

%e a(7) = 14 (= 17 - 3); ...

%e a(54) = 247 (= 251 - 4);

%e a(55) = 252 (= 257 - 5).

%p 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

%t #-IntegerLength[#,4]&/@Prime[Range[60]] (* _Harvey P. Dale_, Dec 14 2015 *)

%o (PARI) a(n) = my(p=prime(n)); p - #digits(p, 4); \\ _Michel Marcus_, Mar 03 2019

%Y Cf. A000040, A004678, A163291, A163293 (analog in base 2).

%K nonn,base

%O 1,2

%A _Juri-Stepan Gerasimov_, Jul 24 2009