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%I #13 Mar 29 2015 16:24:27
%S 9,12,15,18,22,30,38,42,46,55,60,68,81,87,102,105,108,114,120,127,139,
%T 144,149,155,165,175,181,186,195,200,215,228,232,241,247,253,260,265,
%U 270,278,291,306,312,318,333,341,352,357,363,381,387,399,420,426,431
%N Numbers that are the arithmetic mean of four successive primes.
%F 4*n = A000040(i) + A000040(i+1) + A000040(i+2) + A000040(i+3) for some i>=1.
%e a(1) = 9 because (5+7+11+13)/4=9;
%e a(2) = 12 because (7+11+13+17)/4=12;
%e a(3) = 15 because (11+13+17+19)/4=15.
%t Select[ Table[ Sum[ Prime[i], {i, n, n + 3}]/4, {n, 83}], IntegerQ[ # ] &] (* _Robert G. Wilson v_, Feb 04 2005 *)
%t Select[MovingAverage[Prime[Range[500]],4],IntegerQ] (* _Harvey P. Dale_, Aug 10 2012 *)
%Y Cf. A034963.
%K easy,nonn
%O 1,1
%A _Giovanni Teofilatto_, Feb 02 2005
%E Edited by _Robert G. Wilson v_ and _W. Neville Holmes_, Feb 04 2005
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