A069621 a(1) = 9; a(2n) = smallest prime that is a right concatenation of a(2n-1) and a number with no insignificant zeros and a(2n+1) = smallest prime ending in ( the least significant digits) a(2n). Alternate left and right concatenation yielding primes.
9, 97, 197, 1973, 31973, 319733, 3319733, 331973311, 6331973311, 633197331131, 5633197331131, 563319733113127, 6563319733113127, 65633197331131279, 3465633197331131279, 346563319733113127933, 18346563319733113127933
Offset: 1
Examples
a(4) = 1973 starting with a(3) =197 and a(5) = 31973 ending in a(4) = 1973.
Crossrefs
Extensions
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003