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A242383 Lesser of consecutive primes whose average is an oblong number. 2
5, 11, 29, 41, 53, 71, 239, 337, 419, 461, 503, 547, 599, 647, 863, 1051, 1187, 1481, 1721, 1801, 2549, 2647, 2969, 3539, 4421, 6317, 7129, 8009, 10301, 12653, 13567, 14033, 17291, 18353, 19181, 19457, 20021, 22943, 23561, 24179, 27059, 29063, 29753, 31151, 33301, 35153 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..46.

EXAMPLE

53 is in the sequence because it is prime, nextprime(53) = 59 and (53+59)/2 = 56 = 8*7, an oblong number.

PROG

(PARI){for(i=3, 10^5, if(isprime(i), k=(i+nextprime(i+1))/4; if(issquare(8*k+1), print1(i, ", "))))}

CROSSREFS

Cf. A154634.

Sequence in context: A019345 A279067 A049489 * A141785 A144311 A074367

Adjacent sequences:  A242380 A242381 A242382 * A242384 A242385 A242386

KEYWORD

nonn

AUTHOR

Antonio Roldán, May 12 2014

STATUS

approved

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Last modified December 5 23:35 EST 2019. Contains 329783 sequences. (Running on oeis4.)