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A056931 Difference between n-th pronic [=n(n+1)] and average of smallest prime greater than n^2 and largest prime less than (n+1)^2. 5
0, 0, 0, 0, 0, -1, -1, 0, 3, -1, -2, -1, 0, 1, 2, 1, -3, -2, 0, 1, 1, -4, 2, -2, 0, 3, -1, 0, 0, -2, -3, 0, -3, 0, 0, 0, 3, 0, 5, -4, -6, -5, -3, 0, -6, 1, -2, 6, 2, -2, 1, -2, 0, 1, 9, 0, 2, -2, -3, 2, -1, -9, 1, 1, 2, -1, -6, -6, -1, -3, 0, 0, 0, 6, -1, -3, 3, -2, -7, 1, -2, 1, 2, -1, -4 (list; graph; refs; listen; history; text; internal format)
OFFSET

2,9

COMMENTS

a(1)=-0.5 which is not an integer

LINKS

Table of n, a(n) for n=2..86.

FORMULA

a(n) =A002378(n)-(A007491(n)+A053001(n+1))/2 =A002378(n)-A056930(n).

EXAMPLE

a(4)=0 because smallest prime greater than 4^2 is 17, largest prime less than 5^2 is 23, average of 17 and 23 is 20 and 4*5-20=0

MAPLE

with(numtheory): A056931 := n-> n*(n+1)-(prevprime((n+1)^2)+nextprime(n^2))/2);

CROSSREFS

Cf. A002378, A007491, A053000, A053001, A056927, A056928, A056929, A056930.

Sequence in context: A261349 A227962 A255615 * A139569 A201590 A235358

Adjacent sequences:  A056928 A056929 A056930 * A056932 A056933 A056934

KEYWORD

easy,sign

AUTHOR

Henry Bottomley, Jul 12 2000

EXTENSIONS

More terms from James A. Sellers, Jul 13 2000

STATUS

approved

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Last modified February 21 01:29 EST 2019. Contains 320364 sequences. (Running on oeis4.)