A089365 Smallest prime whose product of digits is 2^n.

11, 2, 41, 181, 281, 1481, 881, 4481, 18481, 48281, 48481, 228881, 284881, 828881, 884881, 4448881, 4848881, 18848881, 24888881, 48888841, 88884881, 188888881, 888828881, 848888881, 4848488881, 4488888881, 18848888881, 28888884881

Offset

0,1

Links

Chai Wah Wu, Table of n, a(n) for n = 0..1000

Example

a(8) = 24481 and the digital product is 2^8.

Mathematica

NextPrim[n_] := Block[{k = n + 1}, While[ ! PrimeQ[k], k++ ]; k]; a = Table[0, {24}]; p = 2; Do[q = Log[2, Times @@ IntegerDigits[p]]; If[q != 0 && IntegerQ[q] && a[[q]] == 0, a[[q]] = p; Print[q, " = ", p]]; p = NextPrim[p], {n, 1, 10^9}]  (* Robert G. Wilson v, Nov 08 2003 *)
For a(8): a = Map[ FromDigits, Join[{0}, #, {1}] & /@ Permutations[{2, 8, 8 }]]; Min[ Select[a, PrimeQ[ # ] & ]] (* Robert G. Wilson v, Nov 08 2003 *)

Crossrefs

Cf. A088653, A090840, A091465, A090841, A089298.

Sequence in context: A298439 A095157 A110767 * A130217 A096044 A160464

Adjacent sequences: A089362 A089363 A089364 * A089366 A089367 A089368

Keyword

base,nonn

Author

Amarnath Murthy, Nov 07 2003

Extensions

Edited, corrected and extended by Robert G. Wilson v, Nov 08 2003

a(24)-a(25) corrected by Chai Wah Wu, Aug 15 2017

Status

approved