A094903 Average of 4 primes where the integer Schwarzian derivative is zero.

520, 2397, 3500, 3518, 3826, 4439, 4662, 6620, 7518, 8926, 9206, 10220, 10780, 10938, 12498, 12640, 12740, 14049, 14358, 18623, 20118, 20262, 22569, 24419, 25300, 25706, 26920, 27498, 28482, 29500, 30398, 30438, 31600, 31820, 31986

Offset

4,1

Links

Table of n, a(n) for n=4..38.

Formula

a(n) = if Sf(Prime[n])=0 then (Prime[n-3]+Prime[n-2]+Prime[n-1]+Prime[n])/2

Mathematica

f1[n_]=Prime[n]-Prime[n-1] f2[n_]=Prime[n]-2*Prime[n-1]+Prime[n-2] f3[n_]=Prime[n]-3*Prime[n-1]+3*Prime[n-2]-Prime[n-3] sf[n_]=f3[n]/f1[n]-1.5*(f2[n]/f1[n])^2 a=Delete[Union[Table[If[sf[n]==0, (Prime[n-3]+Prime[n-2]+Prime[n-1]+Prime[n])/2, 0], {n, 4, 2004}]], 1]

Crossrefs

Sequence in context: A235274 A147854 A147856 * A250693 A200427 A250678

Adjacent sequences: A094900 A094901 A094902 * A094904 A094905 A094906

Keyword

nonn

Author

Roger L. Bagula, Jun 15 2004

Status

approved