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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
9, 97, 197, 1973, 31973, 319733, 3319733, 331973311, 6331973311, 633197331131, 5633197331131, 563319733113127, 6563319733113127, 65633197331131279, 3465633197331131279, 346563319733113127933, 18346563319733113127933 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..17.

EXAMPLE

a(4) = 1973 staring with a(3) =197 and a(5) = 31973 ending in a(4) = 1973.

CROSSREFS

Cf. A053582, A069605, A069606, A069607, A069608, A069609, A069610, A069611, A069613, A069614, A069615, A069616, A069617, A069618, A069619, A069620.

Sequence in context: A081131 A158489 A069636 * A284668 A232229 A240780

Adjacent sequences:  A069618 A069619 A069620 * A069622 A069623 A069624

KEYWORD

nonn,base

AUTHOR

Amarnath Murthy, Mar 27 2002

EXTENSIONS

More terms from Antonio G. Astudillo (afg_astudillo(AT)lycos.com), Mar 30 2003

STATUS

approved

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Last modified August 20 14:06 EDT 2019. Contains 326152 sequences. (Running on oeis4.)