|
| |
|
|
A154389
|
|
Nonprimes with largest digit = odd nonprime.
|
|
0
| |
|
|
1, 9, 10, 39, 49, 69, 90, 91, 92, 93, 94, 95, 96, 98, 99, 100, 110, 111, 119, 129, 159, 169, 189, 190, 192, 194, 195, 196, 198, 209, 219, 249, 259, 279, 289, 290, 291, 292, 294, 295, 296, 297, 298, 299, 309, 319, 329, 339, 369, 390, 391, 392, 393, 394, 395, 396
(list; graph; refs; listen; history; internal format)
|
|
|
|
OFFSET
| 1,2
|
|
|
EXAMPLE
| If 1=nonprime and 1(largest digit)=odd nonprime, then 1=a(1). If 9=nonprime and 9(largest digit)=odd nonprime, then 9=a(2). If 10=nonprime, 1>0 and 1(largest digit)=odd nonprime, then 10=a(3). If 39=nonprime, 3<9 and 9(largest digit)=odd nonprime, then 39=a(4), etc.
|
|
|
MAPLE
| Contribution from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 05 2010: (Start)
A141468 := proc(n) option remember; if n <= 3 then op(n, [0, 1, 4]) ; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; end do: end if; end proc:
A054055 := proc(n) max( op(convert(n, base, 10)) ) ; end proc:
for n from 1 to 500 do c := A141468(n) ; if A054055(c) in {1, 9} then printf("%d, ", c ) ; end if; end do: (End)
|
|
|
MATHEMATICA
| ldQ[n_] := Module[{midn = Max[IntegerDigits[n]]}, OddQ[midn] && !PrimeQ[midn]]
Select[Complement[Range[450], Prime[Range[PrimePi[450]]]], ldQ] (* From Harvey P. Dale, Jan 31 2011 *)
|
|
|
CROSSREFS
| Cf. Nonprimes in A141468.
Sequence in context: A007252 A119209 A038206 * A041172 A045913 A156857
Adjacent sequences: A154386 A154387 A154388 * A154390 A154391 A154392
|
|
|
KEYWORD
| nonn,base
|
|
|
AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)ranmbler.ru.), Jan 08 2009
|
|
|
EXTENSIONS
| Corrected (69 inserted, 111 inserted, 189 inserted...) by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), May 05 2010
|
| |
|
|
