|
|
A218209
|
|
Number of n-digit primes that are of the form (k-2)^2 + (k-1)^2 + k^2
|
|
4
|
|
|
2, 1, 3, 4, 12, 31, 86, 230, 681, 1934, 5634, 15772
(list;
graph;
refs;
listen;
history;
text;
internal format)
|
|
|
OFFSET
|
1,1
|
|
LINKS
|
|
|
FORMULA
|
|
|
MATHEMATICA
|
n = -1; Table[cnt = 0; While[n++; p = 3*n^2 + 2; p < 10^e, If[PrimeQ[p], cnt++]]; n--; cnt, {e, 10}] (* T. D. Noe, Oct 23 2012 *)
Table[Count[Table[Total[Range[n, n+2]^2], {n, -1, 600000}], _?(PrimeQ[#] && IntegerLength[#]==k&)], {k, 12}] (* Harvey P. Dale, Oct 17 2016 *)
|
|
CROSSREFS
|
|
|
KEYWORD
|
nonn,base
|
|
AUTHOR
|
|
|
STATUS
|
approved
|
|
|
|