The On-Line Encyclopedia of Integer Sequences (OEIS)

Revision History for A341599

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A341599

Primes p such that p + 2*Sum({k > 0 : p+k and p-k are both prime}) is prime.
(history; published version)

#9 by N. J. A. Sloane at Wed Feb 17 15:06:09 EST 2021

STATUS

reviewed

approved

#8 by Hugo Pfoertner at Tue Feb 16 15:14:35 EST 2021

STATUS

proposed

reviewed

#7 by Robert Israel at Tue Feb 16 14:30:43 EST 2021

STATUS

editing

proposed

#6 by Robert Israel at Tue Feb 16 14:30:38 EST 2021

LINKS

Robert Israel, <a href="/A341599/b341599.txt">Table of n, a(n) for n = 1..10000</a>

STATUS

approved

editing

#5 by Susanna Cuyler at Tue Feb 16 01:04:53 EST 2021

STATUS

proposed

approved

#4 by Robert Israel at Tue Feb 16 00:55:00 EST 2021

STATUS

editing

proposed

#3 by Robert Israel at Tue Feb 16 00:54:55 EST 2021

MAPLE

isprime(n + 2*add(`if`(isprime(n+i) and isprime(n-i), i, 0), i=26..n-5, 6) + `if`(isprime(2, *n - 3), 2*n-6, 0))

#2 by Robert Israel at Tue Feb 16 00:10:58 EST 2021

NAME

allocated for Robert IsraelPrimes p such that p + 2*Sum({k > 0 : p+k and p-k are both prime}) is prime.

DATA

2, 3, 19, 29, 47, 59, 61, 73, 103, 109, 149, 173, 179, 199, 227, 271, 379, 383, 463, 467, 479, 499, 509, 541, 557, 593, 607, 673, 733, 761, 829, 947, 953, 1019, 1049, 1061, 1063, 1109, 1259, 1307, 1319, 1373, 1399, 1489, 1607, 1699, 1709, 1721, 1723, 1741, 1801, 1889, 1931, 1979, 1987, 2029, 2039

OFFSET

1,1

EXAMPLE

a(4) = 29 is a term because the values of k for which 29+k and 29-k are prime are 12, 18 and 24, and 19+2*(12+18+24) = 127 which is prime.

MAPLE

filter:= proc(n) local i;

isprime(n + 2*add(`if`(isprime(n+i) and isprime(n-i), i, 0), i=2..n-2, 2))

end proc:

select(filter, [seq(ithprime(i), i=1..1000)]);

KEYWORD

allocated

nonn

AUTHOR

J. M. Bergot and Robert Israel, Feb 15 2021

STATUS

approved

editing

#1 by Robert Israel at Tue Feb 16 00:10:58 EST 2021

NAME

allocated for Robert Israel

KEYWORD

allocated

STATUS

approved