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A211181 Numbers n such that (n+1)^2 + n and (n+1)^2 - n are both prime. 1
1, 2, 3, 5, 8, 12, 14, 15, 20, 27, 38, 54, 59, 69, 75, 99, 119, 143, 147, 153, 162, 168, 173, 192, 194, 218, 245, 287, 293, 329, 342, 348, 357, 392, 395, 404, 447, 455, 489, 495, 500, 518, 540, 560, 572, 603, 605, 609, 624, 762, 768, 785, 855, 920, 993 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Paul Tek, Table of n, a(n) for n = 1..10000

Sequences related to Legendre's conjecture - Jonathan Sondow, Feb 12 2013

EXAMPLE

n=1,   (n+1)=2;   (n+1)^2=4;     4+1=5           and 4-1=3

n=173, (n+1)=174; (n+1)^2=30276; 30276+173=30449 and 30276-173=30103

n=192, (n+1)=193; (n+1)^2=37249; 37249+192=37441 and 37249-192-37057

MATHEMATICA

Select[ Range[1000], PrimeQ[(# + 1)^2 + #] && PrimeQ[(# + 1)^2 - #] &] (* Jonathan Sondow, Feb 12 2013 *)

PROG

Input "n"'n:Lbl colorin:(n+1)^2-n->rtl:(n+1)^2+n->rtm:if IsPrime (rtm) and

isPrime (rtl) Then:Disp n:Pause:Endif:n+1->n:Goto colorin:EndPrgm

Texas Instruments Basic

CROSSREFS

Sequence in context: A176746 A067288 A308075 * A028766 A022487 A305377

Adjacent sequences:  A211178 A211179 A211180 * A211182 A211183 A211184

KEYWORD

nonn

AUTHOR

César Aguilera, Feb 11 2013

EXTENSIONS

More terms from Jonathan Sondow, Feb 12 2013

STATUS

approved

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Last modified September 27 13:39 EDT 2020. Contains 337380 sequences. (Running on oeis4.)