A372448 a(n) is the 2-adic valuation of 1 + 3*{the n-th iterate of 27 with A371094}.

1, 4, 9, 19, 39, 79, 160, 322, 645, 1292, 2585, 5171, 10344, 20689, 41379, 82759, 165520, 331043, 662087, 1324175, 2648352, 5296705, 10593412, 21186825, 42373651, 84747303, 169494607, 338989215, 677978433, 1355956867, 2711913735, 5423827471, 10847654946, 21695309894, 43390619790, 86781239584, 173562479171, 347124958343

Offset

0,2

Links

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

Formula

a(n) = A371093(A372444(n)).

a(0) = 1, and for n > 0, a(n) = 2*a(n-1) + A371093(A372443(n)).

Prog

(PARI)
A000265(n) = (n>>valuation(n, 2));
A372443(n) = { my(x=27); while(n, x=A000265(3*x+1); n--); (x); };
A371093(n) = valuation(1+3*n, 2);
A372448(n) = if(!n, 1, 2*A372448(n-1)+A371093(A372443(n)));

Crossrefs

Cf. A371093, A371094, A372443, A372444, A372447, A372449.

Sequence in context: A009885 A052549 A153894 * A301137 A214318 A300438

Adjacent sequences: A372445 A372446 A372447 * A372449 A372450 A372451

Keyword

nonn

Author

Antti Karttunen, May 04 2024

Status

approved