

A337148


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


0



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
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OFFSET

0,1


LINKS



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



KEYWORD

base,nonn


AUTHOR



EXTENSIONS



STATUS

approved



