A284891 Concatenation of the numbers from 3 to n.

3, 34, 345, 3456, 34567, 345678, 3456789, 345678910, 34567891011, 3456789101112, 345678910111213, 34567891011121314, 3456789101112131415, 345678910111213141516, 34567891011121314151617, 3456789101112131415161718, 345678910111213141516171819

Offset

3,1

Comments

The a(3) = 3, a(19) = 345678910111213141516171819 are primes in this sequence (for n < 2800).

Links

Table of n, a(n) for n=3..19.

Eric Weisstein's World of Mathematics, Consecutive Number Sequences

Crossrefs

Cf. A089987, A262571.

Sequence in context: A246384 A066265 A268802 * A231593 A367509 A134491

Adjacent sequences: A284888 A284889 A284890 * A284892 A284893 A284894

Keyword

base,nonn,easy

Author

XU Pingya, Apr 05 2017

Status

approved