|
|
A184593
|
|
5n - A101306: sum_{i=1..n} the last digit of prime(i).
|
|
2
|
|
|
3, 5, 5, 3, 7, 9, 7, 3, 5, 1, 5, 3, 7, 9, 7, 9, 5, 9, 7, 11, 13, 9, 11, 7, 5, 9, 11, 9, 5, 7, 5, 9, 7, 3, -1, 3, 1, 3, 1, 3, -1, 3, 7, 9, 7, 3, 7, 9, 7, 3, 5, 1, 5, 9, 7, 9, 5, 9, 7, 11, 13, 15, 13, 17, 19, 17, 21, 19, 17, 13, 15, 11, 9, 11, 7, 9, 5, 3, 7, 3
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
COMMENTS
|
The differences are always odd since the parity of A101306 and n are always opposite.
Positions where a(n)=2k-1 for k>0; 10, 1, 2, 5, 6, 20, 21, 62, 64, 65, 67, 198, 761, 765, 764, 800, ... - Robert G. Wilson v, Jun 06 2012
|
|
LINKS
|
|
|
FORMULA
|
a(n) = 5*n - Sum_{i=1..n} Prime(i) (mod 10).
|
|
MATHEMATICA
|
f[n_] := 5n - Sum[ Mod[ Prime@ k, 10], {k, n}]; Array[f, 80]
Rest@ FoldList[# + 5 - Mod[Prime@ #2, 10] &, 0, Range@ 80]
|
|
CROSSREFS
|
|
|
KEYWORD
|
base,easy,sign
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|