A372449 a(n) = A000523(A372444(n)); One less than the length of binary expansion of the n-th iterate of 27 with A371094.

4, 7, 12, 23, 44, 84, 165, 326, 650, 1297, 2590, 5177, 10349, 20695, 41386, 82766, 165527, 331048, 662093, 1324181, 2648358, 5296712, 10593418, 21186832, 42373658, 84747311, 169494616, 338989224, 677978441, 1355956875, 2711913744, 5423827481, 10847654953, 21695309901, 43390619796, 86781239588, 173562479173, 347124958346

Offset

0,1

Links

Antti Karttunen, Table of n, a(n) for n = 0..1001

Formula

a(n) = A000523(A372444(n)).

a(0) = A372447(0) = 4, and for n > 0, a(n) = A372447(n) + 2*A372448(n-1).

Prog

(PARI)
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));

Crossrefs

Cf. A371093, A371094, A372443, A372444, A372447, A372448.

Column 14 of A372354.

Sequence in context: A187211 A023624 A123194 * A208668 A243860 A322619

Adjacent sequences: A372446 A372447 A372448 * A372450 A372451 A372452

Keyword

nonn

Author

Antti Karttunen, May 04 2024

Status

approved