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A094903 Average of 4 primes where the integer Schwarzian derivative is zero. 1
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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified May 31 09:30 EDT 2020. Contains 334748 sequences. (Running on oeis4.)