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.
Original entry on oeis.org
9, 97, 197, 1973, 31973, 319733, 3319733, 331973311, 6331973311, 633197331131, 5633197331131, 563319733113127, 6563319733113127, 65633197331131279, 3465633197331131279, 346563319733113127933, 18346563319733113127933
Offset: 1
a(4) = 1973 starting with a(3) =197 and a(5) = 31973 ending in a(4) = 1973.
Cf.
A053582,
A069605,
A069606,
A069607,
A069608,
A069609,
A069610,
A069611,
A069613,
A069614,
A069615,
A069616,
A069617,
A069618,
A069619,
A069620.
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
A069620
a(1) = 8; 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-1). Alternate left and right concatenation yielding primes.
Original entry on oeis.org
8, 83, 283, 2833, 32833, 328331, 2328331, 232833127, 3232833127, 323283312749, 14323283312749, 1432328331274927, 281432328331274927, 28143232833127492741, 3628143232833127492741, 36281432328331274927411
Offset: 1
a(4) = 2833 starting with a(3) = 283 and a(5) = 32833 ending in a(4) = 2833.
Cf.
A053582,
A069605,
A069606,
A069607,
A069608,
A069609,
A069610,
A069611,
A069613,
A069614,
A069615,
A069616,
A069617,
A069618,
A069619.
More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003
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