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A075616 Rearrangement of natural numbers so that starting with a(n) the concatenation of n numbers gives a prime. 2
2, 1, 3, 4, 7, 5, 9, 6, 17, 8, 43, 10, 19, 11, 13, 12, 33, 14, 37, 15, 23, 16, 113, 18, 73, 20, 51, 21, 103, 22, 61, 24, 87, 25, 49, 26, 67, 27, 117, 28, 57, 29, 71, 30, 79, 31, 283, 32, 239, 34, 81, 35, 143, 36, 151, 38, 139, 39, 147, 40, 289, 41, 161, 42, 351, 44, 129, 45 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..68.

MATHEMATICA

a = {2, 1, 3}; f[n_] := Block[{k = 1, b = Take[a, {n, 2n - 3}]}, While[Position[a, k] != {}, k++ ]; b = Join[b, IntegerDigits[k]]; a = Append[a, k]; While[ Position[a, k] != {} || !PrimeQ[ FromDigits[ Join[ b, IntegerDigits[k]]]], k++ ]; a = Append[a, k]]; Do[ f[n], {n, 3, 40}]; a

CROSSREFS

Cf. A075617 and A073672.

Sequence in context: A192439 A160187 A257879 * A160186 A050041 A058658

Adjacent sequences:  A075613 A075614 A075615 * A075617 A075618 A075619

KEYWORD

base,nonn

AUTHOR

Amarnath Murthy, Sep 29 2002

EXTENSIONS

Edited and extended by Robert G. Wilson v, Oct 02 2002

STATUS

approved

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Last modified March 23 05:36 EDT 2019. Contains 321422 sequences. (Running on oeis4.)