A262571 Concatenation of the numbers from 2 to n.

2, 23, 234, 2345, 23456, 234567, 2345678, 23456789, 2345678910, 234567891011, 23456789101112, 2345678910111213, 234567891011121314, 23456789101112131415, 2345678910111213141516, 234567891011121314151617, 23456789101112131415161718, 2345678910111213141516171819

Offset: 2

Author

N. J. A. Sloane, Sep 25 2015

Keywords

• nonn
• base

Crossrefs

For primes in this sequence see A089987.

Cf. A007908, A262299, A262572-A262582.

See A262300 for more about this problem.

Programs

Magma

[Seqint(Reverse(&cat[Reverse(Intseq(k)): k in [2..n]])): n in [2..20]]; // Vincenzo Librandi, Oct 29 2018

Mathematica

Table[FromDigits[Flatten[IntegerDigits[Range[2, n]]]], {n, 2, 19}]  (* Robert Price, Oct 28 2018 *)

Python

def a(n): return int("".join(map(str, range(2, n+1))))
print([a(n) for n in range(2, 20)]) # Michael S. Branicky, Feb 23 2021