A108065 Numbers n such that DENEAT(n!) is prime, where DENEAT(n) = concatenate number of even digits in n, number of odd digits and total number of digits.

1, 2, 3, 10, 15, 29, 35, 39, 51, 65, 167, 185, 198, 250, 282, 325, 366, 368, 382, 396, 400, 403, 450, 453, 509, 574, 575, 590, 598, 601, 699, 720, 759, 764, 788, 791, 797, 817, 824, 860, 863, 865, 867, 877, 901, 909, 911, 913, 930, 936, 1066, 1068, 1081, 1145

Offset

1,2

Links

Harvey P. Dale, Table of n, a(n) for n = 1..1000

Example

10 is in the sequence because 10! = 3628800 has 6 even digits, 1
odd digit and 7 total digits, yielding the prime 617.

Mathematica

eotQ[n_]:=Module[{idnf=IntegerDigits[n!], len, ev, od}, len=Length[idnf]; ev= Count[ idnf, _?EvenQ]; od=Count[idnf, _?OddQ]; PrimeQ[FromDigits[ Flatten[ IntegerDigits/@ Join[{ev, od, len}]]]]]; Select[Range[1200], eotQ] (* Harvey P. Dale, Jul 05 2017 *)

Crossrefs

Cf. A073053.

Sequence in context: A348475 A075770 A135101 * A187767 A226881 A369781

Adjacent sequences: A108062 A108063 A108064 * A108066 A108067 A108068

Keyword

base,nonn

Author

Jason Earls, Jun 03 2005

Status

approved