OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
9 (composite) is a term because 9 + 1 = 10 (even composite);
22 (composite) is a term because 2 + 2 = 4 (even composite);
34 (composite) is a term because 3 + 1 = 4 (even composite).
MAPLE
frequdig := proc(n, dig) local f, d ; f := 0 ; for d in convert(n, base, 10) do if d = dig then f :=f+1; end if; end do; f ; end proc:
A054054 := proc(n) min(op(convert(n, base, 10)) ) ; end proc:
for n from 1 to 500 do c := A002808(n) ; sdg := A054054(c) ; a := sdg +frequdig(c, sdg) ; if type(a, 'even') and not isprime(a) then printf("%d, ", c ) ; end if; end do: # R. J. Mathar, May 05 2010
MATHEMATICA
ecQ[n_]:=Module[{idn=IntegerDigits[n], s, c}, s=Min[idn]; c=s+Count[idn, s]; EvenQ[c]&&AllTrue[ {n, c}, CompositeQ]]; Select[Range[400], ecQ] (* Harvey P. Dale, Jul 19 2023 *)
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Juri-Stepan Gerasimov, Jan 11 2009
EXTENSIONS
Corrected (28 replaced with 38, 269 with 369) by R. J. Mathar, May 05 2010
Name and Example section edited by Jon E. Schoenfield, Feb 11 2019
STATUS
approved