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A329876 Lexicographically earliest sequence of positive integers such that for n > 1, the concatenation of a(n), a(n-1), ..., a(1), in decimal, is a prime number. 2
1, 1, 2, 4, 3, 2, 4, 15, 3, 9, 20, 4, 3, 11, 31, 6, 24, 23, 82, 11, 21, 3, 22, 20, 63, 19, 56, 22, 17, 42, 105, 31, 2, 4, 27, 96, 42, 5, 72, 19, 20, 22, 32, 102, 31, 104, 4, 24, 95, 21, 13, 12, 9, 38, 3, 58, 38, 78, 31, 119, 31, 45, 107, 42, 12, 9, 21, 66, 181 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

COMMENTS

For any n > 0, the concatenation of a(n+1) and A053582(n) gives A053582(n+1).

LINKS

Rémy Sigrist, Table of n, a(n) for n = 1..501

FORMULA

The first terms, alongside their concatenations, are:

  n   a(n)  A053582(n)

  --  ----  -----------

   1     1            1

   2     1           11

   3     2          211

   4     4         4211

   5     3        34211

   6     2       234211

   7     4      4234211

   8    15    154234211

   9     3   3154234211

  10     9  93154234211

PROG

(PARI) print1 (v=1); for (n=2, 69, s=(b=10)^#digits(v, b); for (k=1, oo, if (isprime(v+=s), print1 (", "k); break)))

CROSSREFS

See A053582 for the corresponding concatenations.

Sequence in context: A152026 A060806 A320044 * A128868 A095986 A212637

Adjacent sequences:  A329873 A329874 A329875 * A329877 A329878 A329879

KEYWORD

nonn,base

AUTHOR

Rémy Sigrist, Nov 23 2019

STATUS

approved

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Last modified February 17 12:32 EST 2020. Contains 331996 sequences. (Running on oeis4.)