OFFSET
1,1
EXAMPLE
a(1) = 9 because (5+7+11+13)/4=9;
a(2) = 12 because (7+11+13+17)/4=12;
a(3) = 15 because (11+13+17+19)/4=15.
MATHEMATICA
Select[ Table[ Sum[ Prime[i], {i, n, n + 3}]/4, {n, 83}], IntegerQ[ # ] &] (* Robert G. Wilson v, Feb 04 2005 *)
Select[MovingAverage[Prime[Range[500]], 4], IntegerQ] (* Harvey P. Dale, Aug 10 2012 *)
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Giovanni Teofilatto, Feb 02 2005
EXTENSIONS
Edited by Robert G. Wilson v and W. Neville Holmes, Feb 04 2005
STATUS
approved