A264980 - OEIS

%I #15 Dec 29 2015 11:23:30

%S 1,2,4,8,16,64,32,184,352,704,1408,1880,2824,14032,10328,56128,100576,

%T 145784,189472,370304,731752,4388248,2924096,11175712,15965704,

%U 31930448,63861880,383165344,255439712,1021772344,510875648,2550188248,5619691648,9689861048,17830350904,79068724264,34109913224,192259976368,133338241880

%N Base-3 reversal of 2^n: a(n) = A030102(A000079(n)).

%H Antti Karttunen, <a href="/A264980/b264980.txt">Table of n, a(n) for n = 0..512</a>

%F a(n) = A030102(A000079(n)) = A263273(A000079(n)).

%F a(0) = 1, for n >= 1, a(n) = A265342(a(n-1)).

%e 2^5 = 32 in base 3 = "1012" (= A007089(32)) as 1*27 + 1*3 + 2*1 = 32. 2^6 = 64 in base 3 = "2101" as 2*27 + 1*9 + 1*1 = 64. "1012" reversed is "2101" and vice versa, thus a(5) = 64 and a(6) = 32.

%o (Scheme, two alternatives)

%o (define (A264980 n) (A030102 (A000079 n)))

%o (define (A264980 n) (if (zero? n) 1 (A265342 (A264980 (- n 1)))))

%o (PARI) base(n) = {my(a=[n%3]); while(0<n\=3, a=concat(n%3, a)); a}

%o a(n) = subst(Polrev(base(2^n)), x, 3); \\ _Altug Alkan_, Dec 29 2015

%Y Leftmost column of A265345.

%Y Cf. A000079, A007089, A030102, A263273, A265210, A265342.

%Y Cf. also A036215.

%K nonn,base

%O 0,2

%A _Antti Karttunen_, Dec 05 2015