OFFSET
1,1
LINKS
M. F. Hasler, Table of n, a(n) for n = 1..17495
Sylvester Smith, A Set of Conjectures on Smarandache Sequences, Bulletin of Pure and Applied Sciences, (Bombay, India), Vol. 15 E (No. 1), 1996, pp. 101-107.
EXAMPLE
113 is member as 11 and 3 are primes.
a(12)=227 = "2"+"2"+"7" is the first term not in A105184 (restricted to concatenation of two primes). [M. F. Hasler, Oct 15 2009]
PROG
(PARI) is_A019549(n, recurse=0)={ isprime(n) == recurse & return(recurse); for(i=1, #Str(n)-1, isprime( n%10^i ) & is_A019549( n\10^i, 1) & n\10^(i-1)%10 & return(1)) } \\ M. F. Hasler, Oct 15 2009
(Python)
def c(n, m):
if m > 0 and isprime(n): return True
s = str(n)
return any(s[i]!="0" and isprime(int(s[:i])) and c(int(s[i:]), m+1) for i in range(1, len(s)))
def ok(n): return isprime(n) and c(n, 0)
print([k for k in range(978) if ok(k)]) # Michael S. Branicky, Sep 01 2024
CROSSREFS
KEYWORD
nonn,base
AUTHOR
R. Muller
STATUS
approved