A102252 Slowest increasing sequence beginning with 1 whose digits satisfy the rule d*2.

1, 2, 4, 8, 16, 21, 24, 248, 481, 681, 6212, 16212, 42421, 242484, 842484, 8168168, 48168162, 121621216, 816212162, 1242421242, 4212162124, 24212424848, 42484842421, 242484842484, 816816848168, 1684842484816, 8168481681621

Offset

1,2

Comments

Same digits as A061581.

Links

Table of n, a(n) for n=1..27.

Formula

d*2, beginning with 1.

Example

Read a(5)=16, which produces first digit of a(6)=2 because 1*2=2 and second digit of a(6)=1 and first digit of a(7)=2 because 6*2=12.

Mathematica

t = Flatten[ NestList[ Function[x, Flatten[ IntegerDigits[2IntegerDigits[ x]]]], 1, 17]]; a = 0; l = {}; Do[k = 1; While[fd = FromDigits[ Take[t, k]]; a >= fd, k++ ]; t = Drop[t, k]; AppendTo[l, fd]; a = fd, {n, 27}]; l (* Robert G. Wilson v, Feb 21 2005 *)

Crossrefs

Cf. A061581.

Sequence in context: A244484 A350414 A045776 * A174838 A308149 A196871

Adjacent sequences: A102249 A102250 A102251 * A102253 A102254 A102255

Keyword

base,easy,nonn

Author

Alexandre Wajnberg and Eric Angelini, Feb 18 2005

Extensions

More terms from Robert G. Wilson v, Feb 21 2005

Status

approved