A337148 Concatenation of sum n+(n+1) and product n*(n+1) in decimal.

10, 32, 56, 712, 920, 1130, 1342, 1556, 1772, 1990, 21110, 23132, 25156, 27182, 29210, 31240, 33272, 35306, 37342, 39380, 41420, 43462, 45506, 47552, 49600, 51650, 53702, 55756, 57812, 59870, 61930, 63992, 651056, 671122, 691190, 711260, 731332, 751406, 771482

Offset

0,1

Links

Table of n, a(n) for n=0..38.

Eric Weisstein's World of Mathematics, Concatenation

Formula

a(n) = (2n+1)*10^b + n^2 + n, where b is length of n^2 + n.

Example

For n = 0: n+1 = 1; 0+1 is 1 and 0*1 is 0. So concatenate to a(0) = 10.
For n = 1: n+1 = 2; 1+2 is 3 and 1*2 is 2. So a(1) = 32.
For n = 10: n+1 = 11; 10+11 is 21 and 10*11 is 110. So a(10) = 21110.

Mathematica

Table[(2n+1)*10^Length[IntegerDigits[n^2+n]]+n^2+n, {n, 0, 38}] (* Stefano Spezia, Jan 29 2021 *)

Prog

(Python)
def concatenate(n):
    return (2*n+1)*10**len(str(n**2+n))+ n**2+n

Crossrefs

Cf. A002378, A005408.

Sequence in context: A008422 A063926 A239834 * A202804 A155192 A229720

Adjacent sequences: A337145 A337146 A337147 * A337149 A337150 A337151

Keyword

base,nonn

Author

Ercan Isik, Jan 27 2021

Extensions

More terms from Stefano Spezia, Jan 29 2021

Status

approved