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 A328282 #9 Oct 14 2019 14:31:24 %S A328282 1,3,2,15,6,4,5,255,30,12,13,16,9,11,10,65535,510,60,61,48,25,27,26, %T A328282 256,33,19,18,47,22,20,21,4294967295,131070,1020,1021,240,121,123,122, %U A328282 768,97,51,50,111,54,52,53,65536,513,67,66,79,38,36,37,767,94,44,45 %N A328282 a(n) is the least k such that A175930(k) = n. %C A328282 To compute a(n): %C A328282 - the binary representation of n has k = A000120(n) one bits, %C A328282 - the binary representation of a(n) has k runs of consecutive equal bits, %C A328282 - the length of the i-th run in a(n) has length 2^z where z is the number of zeros immediately following the i-th one bit in the binary representation of n, %C A328282 - this division into sections starting with ones in n or corresponding to a run in a(n) is materialized by slashes in the example section. %F A328282 a(n) <= 2^n-1 with equality iff n is a power of 2. %F A328282 A005811(a(n)) = A000120(n). %e A328282 The first terms, alongside the binary representation of n and of a(n) with peer sections separated by slashes, are: %e A328282 n a(n) bin(n) bin(a(n)) %e A328282 -- ----- ------- ---------------- %e A328282 1 1 1 1 %e A328282 2 3 10 11 %e A328282 3 2 1/1 1/0 %e A328282 4 15 100 1111 %e A328282 5 6 10/1 11/0 %e A328282 6 4 1/10 1/00 %e A328282 7 5 1/1/1 1/0/1 %e A328282 8 255 1000 11111111 %e A328282 9 30 100/1 1111/0 %e A328282 10 12 10/10 11/00 %e A328282 11 13 10/1/1 11/0/1 %e A328282 12 16 1/100 1/0000 %e A328282 13 9 1/10/1 1/00/1 %e A328282 14 11 1/1/10 1/0/11 %e A328282 15 10 1/1/1/1 1/0/1/0 %e A328282 16 65535 10000 1111111111111111 %o A328282 (PARI) a(n)={ my (r=[], l, v=0); while (n, r=concat(l=1+valuation(n,2), r); n \= 2^l); for (i=1, #r, v *= 2^2^(r[i]-1); if (i%2, v += 2^2^(r[i]-1)-1)); v } %Y A328282 Cf. A000120, A005811, A175930. %K A328282 nonn,base %O A328282 1,2 %A A328282 _Rémy Sigrist_, Oct 11 2019