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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: A345928 A060806 A320044 * A128868 A341073 A095986 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 September 12 07:57 EDT 2024. Contains 375850 sequences. (Running on oeis4.)