A276025 Next prime after concatenate of n, n times (A000461).

2, 23, 337, 4447, 55579, 666667, 7777801, 88888901, 1000000007, 10101010101010101073, 1111111111111111111189, 121212121212121212121327, 13131313131313131313131439, 1414141414141414141414141451, 151515151515151515151515151607, 16161616161616161616161616161709, 1717171717171717171717171717171741

Offset

1,1

Links

Dana Jacobsen, Table of n, a(n) for n = 1..332 (last entry has 996 digits)

Eric Weisstein's World of Mathematics, Next Prime.

Formula

a(n) = A007918(A000461(n)).

a(n) = A000040(A000720(A000461(n))+1).

Example

a(5) = 55579, since this is the next prime after 55555.

Maple

a:= n-> nextprime(parse(cat(n$n))):
seq(a(n), n=1..20);  # Alois P. Heinz, Aug 18 2016

Mathematica

Table[NextPrime[n ((10^(n Floor[Log[10, 10 n]]) - 1)/(10^Floor[Log[10, 10 n]] - 1)), Plus[1]], {n, 1, 17}]

Prog

(PARI) a000461(n) = my(i=1, k=n); while(i < n, k=eval(Str(k, n)); i++); k
a(n) = nextprime(a000461(n)) \\ Felix Fröhlich, Aug 18 2016
(Perl) use ntheory ":all"; sub a276025 { my $n=shift; next_prime("$n" x $n); } Dana Jacobsen, Aug 22 2016

Crossrefs

Cf. A000040, A000720, A000461, A007918.

Sequence in context: A173935 A216549 A091693 * A211925 A277830 A197740

Adjacent sequences: A276022 A276023 A276024 * A276026 A276027 A276028

Keyword

nonn,base

Author

Ilya Gutkovskiy, Aug 16 2016

Status

approved