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A077914 Sums of two distinct primes in exactly two ways. 8
16, 18, 20, 22, 26, 28, 32, 62, 68 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Most likely no more terms. See A117929. - T. D. Noe, Mar 21 2012

Numbers k such that A117929(k) = 2. - Joerg Arndt, Jun 07 2021

LINKS

Table of n, a(n) for n=1..9.

G. L. Honaker, Jr., Prime Curio for 16, April 2000.

EXAMPLE

22 is a term as 22 = 19+3 = 17+5 are the only two ways to express 22 as a sum of two distinct primes.

MAPLE

P:=proc(q, w) local a, k, n;

for n from 1 to q do a:=0; for k from 1 to trunc(n/2) do

if isprime(k) and isprime(n-k) and n<>2*k then a:=a+1; fi; od;

if a=w then print(n); fi; od; end: P(100, 2); # Paolo P. Lava, May 21 2014

CROSSREFS

Cf. A077969 (3 ways), A078299 (4 ways), A080854 (5 ways), A080862 (6 ways).

Sequence in context: A043705 A178980 A031315 * A273543 A274127 A328736

Adjacent sequences:  A077911 A077912 A077913 * A077915 A077916 A077917

KEYWORD

nonn,more

AUTHOR

Shyam Sunder Gupta, Mar 29 2003

STATUS

approved

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Last modified August 10 06:08 EDT 2022. Contains 356029 sequences. (Running on oeis4.)