A102655 Numbers that are the arithmetic mean of four successive primes.

9, 12, 15, 18, 22, 30, 38, 42, 46, 55, 60, 68, 81, 87, 102, 105, 108, 114, 120, 127, 139, 144, 149, 155, 165, 175, 181, 186, 195, 200, 215, 228, 232, 241, 247, 253, 260, 265, 270, 278, 291, 306, 312, 318, 333, 341, 352, 357, 363, 381, 387, 399, 420, 426, 431

Offset

1,1

Links

Table of n, a(n) for n=1..55.

Formula

4*n = A000040(i) + A000040(i+1) + A000040(i+2) + A000040(i+3) for some i>=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

Cf. A034963.

Sequence in context: A342082 A365408 A161345 * A308748 A120167 A263674

Adjacent sequences: A102652 A102653 A102654 * A102656 A102657 A102658

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