login
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
OFFSET
1,3
COMMENTS
For any n > 0, the concatenation of a(n+1) and A053582(n) gives A053582(n+1).
LINKS
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: A345928 A060806 A320044 * A128868 A341073 A095986
KEYWORD
nonn,base
AUTHOR
Rémy Sigrist, Nov 23 2019
STATUS
approved