This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A381607 #8 Mar 03 2025 09:33:02
%S A381607 0,1,2,3,4,5,6,7,8,8,9,10,11,12,13,14,15,16,16,17,18,19,20,21,22,23,
%T A381607 24,21,22,23,24,25,26,27,28,29,29,30,31,32,33,34,35,36,37,37,38,39,40,
%U A381607 41,42,43,44,45,42,43,44,45,46,47,48,49,50,50,51,52,53,54
%N A381607 For any nonnegative integer n with ternary expansion Sum_{k >= 0} t_k * 3^k, a(n) = Sum_{k >= 0} t_k * A000045(2*k + 2).
%C A381607 Every nonnegative integer appears in the sequence, a finite number of times.
%H A381607 Rémy Sigrist, <a href="/A381607/b381607.txt">Table of n, a(n) for n = 0..6560</a>
%F A381607 a(A028898(A381579(n))) = n.
%e A381607 42 = 3^3 + 3^2 + 2*3^1, so a(42) = A000045(8) + A000045(6) + 2*A000045(4) = 21 + 8 + 2*3 = 35.
%o A381607 (PARI) a(n) = { my (t = Vecrev(digits(n, 3))); sum(k = 1, #t, t[k] * fibonacci(2*k)); }
%Y A381607 See A022290 for a similar sequence.
%Y A381607 Cf. A000045, A028898, A381579.
%K A381607 nonn,base,easy
%O A381607 0,3
%A A381607 _Rémy Sigrist_, Mar 01 2025