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 A381581 #7 Feb 28 2025 12:08:25
%S A381581 1,2,3,4,6,8,12,16,20,21,22,24,27,28,30,40,42,44,45,48,55,56,57,58,60,
%T A381581 66,70,72,75,76,80,84,90,92,95,96,100,102,110,111,112,115,116,120,132,
%U A381581 135,138,140,144,150,152,153,156,168,170,175,176,180,186,190,195,198
%N A381581 Numbers divisible by the sum of the digits in their Chung-Graham representation (A381579).
%C A381581 Numbers k such that A291711(k) divides k.
%C A381581 Analogous to Niven numbers (A005349) with the Chung-Graham representation (A381579) instead of the decimal representation.
%C A381581 A001906(k) = Fibonacci(2*k) is a term for all k >= 1.
%C A381581 If k is not divisible by 3 (A001651), then Fibonacci(2*k) + 1 is a term.
%H A381581 Amiram Eldar, <a href="/A381581/b381581.txt">Table of n, a(n) for n = 1..10000</a>
%e A381581 4 is a term since A291711(4) = 1 divides 4.
%e A381581 6 is a term since A291711(6) = 2 divides 6.
%t A381581 f[n_] := f[n] = Fibonacci[2*n]; q[n_] := Module[{s = 0, m = n, k}, While[m > 0, k = 1; While[m > f[k], k++]; If[m < f[k], k--]; If[m >= 2*f[k], s += 2; m -= 2*f[k], s++; m -= f[k]]]; Divisible[n, s]]; Select[Range[200], q]
%o A381581 (PARI) mx = 20; fvec = vector(mx, i, fibonacci(2*i)); f(n) = if(n <= mx, fvec[n], fibonacci(2*n));
%o A381581 isok(n) = {my(s = 0, m = n, k); while(m > 0, k = 1; while(m > f(k), k++); if(m < f(k), k--); if(m >= 2*f(k), s += 2; m -= 2*f(k), s++; m -= f(k))); !(n % s);}
%Y A381581 Cf. A000045, A001651, A001906, A291711.
%Y A381581 Subsequences: A381582, A381583, A381584, A381585.
%Y A381581 Similar sequences: A005349, A049445, A064150, A328208, A328212.
%K A381581 nonn,easy,base
%O A381581 1,2
%A A381581 _Amiram Eldar_, Feb 28 2025