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A108809 Numbers n such that both n+(n-1)^2 and n+(n+1)^2 are primes. 0
2, 3, 4, 7, 9, 15, 18, 25, 34, 55, 58, 63, 67, 100, 102, 139, 144, 148, 154, 162, 163, 168, 190, 195, 219, 232, 247, 267, 280, 289, 330, 349, 379, 384, 417, 427, 448, 454, 477, 568, 580, 643, 645, 669, 672, 727, 762, 793, 802, 813, 837, 847, 900, 975, 988, 993 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..56.

EXAMPLE

34 is in the sequence because 34 + 33^2 = 1123 and 34 + 35^2 = 1259 are both prime.

MAPLE

L:=[]; for k from 1 to 1000 do if isprime(k+(k-1)^2) and isprime(k+(k+1)^2) then L:=[op(L), k] fi od;

CROSSREFS

Cf. A027861.

Sequence in context: A094093 A240077 A237997 * A027947 A067236 A250255

Adjacent sequences:  A108806 A108807 A108808 * A108810 A108811 A108812

KEYWORD

easy,nonn

AUTHOR

Walter Kehowski, Jul 04 2005

STATUS

approved

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Last modified November 27 00:18 EST 2014. Contains 250152 sequences.