A261396 a(n) = smallest k such that A260273(k) >= 2^n.

1, 2, 3, 4, 7, 12, 19, 34, 61, 110, 200, 371, 697, 1310, 2484, 4739, 9072, 17458, 33671, 65128, 126225, 244802, 475124, 922891, 1793461, 3487348, 6784691, 13208038, 25731600, 50166771, 97873783, 191089176, 373349780, 729972649, 1428257200, 2796453078, 5478981032, 10741710906, 21072415837

Offset

0,2

Comments

The sequence indicates the first time a term in A260273 has binary length n+1.

A261646 = first differences = row lengths of tables A261644 and A261712. - Reinhard Zumkeller, Aug 30 2015

Links

Table of n, a(n) for n=0..38.

Prog

(Haskell)
a261396 n = a261396_list !! (n-1)
a261396_list = f 1 1 a260273_list where
   f z k (x:xs) | x >= z    = k : f (2 * z) (k + 1) xs
                | otherwise = f z (k + 1) xs
-- Reinhard Zumkeller, Aug 30 2015

Crossrefs

Cf. A260273.

Cf. A261646, A261644, A261712.

Sequence in context: A307970 A216604 A211695 * A357532 A018148 A084972

Adjacent sequences: A261393 A261394 A261395 * A261397 A261398 A261399

Keyword

nonn

Author

N. J. A. Sloane, Aug 17 2015

Extensions

a(18)-a(23) from Alois P. Heinz, Aug 19 2015

a(24)-a(34) from Chai Wah Wu, Aug 26 2015

a(35)-a(38) from Chai Wah Wu, Aug 31 2015

Status

approved