OFFSET
2,1
COMMENTS
Conjecture: All the composite positions are occupied by a zero except the most significant digit, which in most cases perhaps is 4. Most of the prime positions for p > 5 are occupied by 2.
EXAMPLE
a(6) = 420221.
MAPLE
with(combinat, cartprod): ds:=proc(s) local j, l: l:=nops(s): RETURN(add(s[j]*10^(l-j), j=1..l)):end: p:=[2, 3, 5, 7]:c:=[0, 4, 6, 8, 9]: cf:=[4, 6, 8, 9]: ctpr:=proc(n, s) local m, T, a: a:=s: m:=1: T:=cartprod([seq(piecewise(isprime(n-i+2), p, i=2, cf, c), i=2..n), [1]]): while not T[finished] do m:=ds(T[nextvalue]()): if isprime(m) and not member(m, a) then a:=[op(a), m]: RETURN(a) fi od: end: a:=[]: for n from 2 to 20 do a:=ctpr(n, a) od: op(a); # C. Ronaldo
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, Nov 10 2003
EXTENSIONS
More terms from C. Ronaldo (aga_new_ac(AT)hotmail.com), Dec 25 2004
STATUS
approved