OFFSET
1,3
LINKS
Max Alekseyev, Table of n, a(n) for n = 1..352 (first 322 terms from Giovanni Resta)
EXAMPLE
n=60: concatenated distinct-prime factor-set for 60th-repunit is:
371113313741611012112412712161354190919901279612906161418890139526741,
its digit sum is 244, so a(60) = 244 - 60 = 184.
The value of this excess-sum is zero if n=2,4,19,23.
MATHEMATICA
a[1] = -1; a[n_] := Total@ Flatten[IntegerDigits /@ First /@ FactorInteger[(10^n - 1)/9]] - n; Array[a, 62] (* Giovanni Resta, Jul 19 2018 *)
CROSSREFS
KEYWORD
sign,base
AUTHOR
Labos Elemer, Jun 22 2004
EXTENSIONS
Data corrected by Giovanni Resta, Jul 19 2018
STATUS
approved