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.
A000265(n) = (n>>valuation(n,2)); A000523(n) = logint(n,2); A372443(n) = { my(x=27); while(n, x=A000265(3*x+1); n--); (x); }; A371093(n) = valuation(1+3*n,2); A372447(n) = A000523(A372443(n)); A372448(n) = if(!n,1,2*A372448(n-1)+A371093(A372443(n))); A372449(n) = if(0==n,A372447(n),A372447(n)+2*A372448(n-1));
The term of A086893 that has same binary length as A372444(0) = 27 is 21 [as 21 = 10101_2 in binary, and 27 = 11011_2 in binary], therefore a(0) = 27-21 = 6. The term of A086893 that has same binary length as A372444(1) = 165 is 213, therefore a(1) = 165-213 = -48.
A000523(n) = logint(n,2); A371094(n) = { my(m=1+3*n, e=valuation(m,2)); ((m*(2^e)) + (((4^e)-1)/3)); }; A372444(n) = { my(x=27); while(n, x=A371094(x); n--); (x); }; A086893(n) = (if(n%2, 2^(n+1), 2^(n+1)+2^(n-1))\3); A372454(n) = { my(x=A372444(n)); (x - A086893(1+A000523(x))); };
A372454(n) = if(!n, A372453(n), (4^A372448(n-1))*A372453(n));
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