A077352 a(n) = (concatenation in ascending order of divisors of 2^n)/2^n.

1, 6, 31, 156, 7801, 390051, 19502551, 9751275501, 4875637750501, 2437818875250501, 12189094376252505001, 60945471881262525005001, 304727359406312625025005001, 1523636797031563125125025005001, 76181839851578156256251250250050001, 3809091992578907812812562512502500050001

Offset

0,2

Links

Paolo Xausa, Table of n, a(n) for n = 0..80

Formula

For n>=1, a(n) = (a(n-1)*2^(n-1)*10^(floor(log_10(2^n))+1)+2^n)/2^n. - Sam Alexander, Feb 27 2005

Example

a(6) = 1248163264/64 = 19502551.

Maple

a:= n-> parse(cat(2^i$i=0..n))/2^n:
seq(a(n), n=0..15);  # Alois P. Heinz, May 16 2025

Mathematica

A077352[n_] := FromDigits[Flatten[IntegerDigits[Divisors[#]]]]/# & [2^n];
Array[A077352, 16, 0] (* or *)
FoldList[10^IntegerLength[2^#2]*#/2 + 1 &, 1, Range[15]] (* Paolo Xausa, May 19 2025 *)

Crossrefs

Cf. A000079, A034887, A059268, A077351, A069872, A077353.

Sequence in context: A026771 A289788 A065096 * A038223 A334650 A022034

Adjacent sequences: A077349 A077350 A077351 * A077353 A077354 A077355

Keyword

base,nonn

Author

Amarnath Murthy, Nov 05 2002

Extensions

Offset corrected by Sean A. Irvine, May 16 2025

Status

approved