1,2

A139244(n-1) = ceiling(c^(2^n)).

The digit 4 appears for the first time only at position n=53, making it the last one to appear in the sequence.

Table of n, a(n) for n=1..74.

A. V. Aho and N. J. A. Sloane, Some doubly exponential sequences, The Fibonacci Quarterly, 11 (1973), 429-437.

1.96689176179017636533350572... .

Cf. A139244.

Sequence in context: A309822 A195365 A092513 * A242713 A155129 A254980

Adjacent sequences: A260312 A260313 A260314 * A260316 A260317 A260318

nonn,cons

Chayim Lowen, Jul 22 2015

approved