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A115989 Numbers k such that the average of primes p(k) and p(k+1) is a power of 3. 3
4, 22, 20700806, 166677978 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..4.

FORMULA

a(n) = A000720(A115986(n)), - Jinyuan Wang, Feb 26 2020

EXAMPLE

p(20700806) = 387420479, p(20700806 + 1) = 387420499 and (387420479 + 387420499)/2 = 387420489 = 3^18, so 20700806 belongs to the sequence.

CROSSREFS

Cf. A000720, A115986, A115987, A115988.

Sequence in context: A065401 A053775 A037142 * A016485 A258024 A258203

Adjacent sequences:  A115986 A115987 A115988 * A115990 A115991 A115992

KEYWORD

nonn,more

AUTHOR

Giovanni Resta, Feb 10 2006

STATUS

approved

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Last modified October 3 18:24 EDT 2022. Contains 357237 sequences. (Running on oeis4.)