A180342 - OEIS

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A180342

a(n) = the smallest number k such that the smallest prime factor of k^2 + 1 equals A002144(n).

2, 34, 4, 46, 6, 50, 76, 194, 100, 144, 366, 10, 730, 324, 374, 254, 286, 266, 886, 274, 14, 794, 610, 546, 16, 456, 494, 334, 724, 964, 520, 526, 834, 664, 1596, 504, 3510, 20, 2720, 1234, 1120, 516, 566, 874, 810, 756, 1134, 2110, 1224, 24, 670, 726 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`1,1`
	COMMENTS	`The sequence giving the smallest number k such that the greatest prime factor of k^2 + 1 equals A002144(n) is A002314.`
	LINKS	`Table of n, a(n) for n=1..52.`
	EXAMPLE	`a(1) = 2 because 2^2 + 1 = 5 = A002144(1) ;` `a(2) = 34 because 34^2 + 1= 1389 = A002144(2) 89 ;` `a(3) = 4 because 4^2 + 1 = 17 = A002144(3) ;` `a(4) = 46 because 46^2 + 1 = 2973 = A002144(4) 73.`
	MAPLE	`with(numtheory):T:=array(1..200):k:=1:for p from 1 to 1000 do: if type(p, prime)=true` and irem(p, 4)=1 then T[k]:=p:k:=k+1:else fi:od:for q from 1 to k do:z:=T[q]:ind:=0:for n from 1 to 10000 while(ind=0) do: x:=n^2+1:y:=factorset(x):if z=y[1] then ind:=1:printf(`%d, `, n):else fi:od: od:
	CROSSREFS	`Cf. A002522, A002144, and A002314.` `Sequence in context: A003820 A112980 A109336 * A098869 A131544 A123284` `Adjacent sequences: A180339 A180340 A180341 * A180343 A180344 A180345`
	KEYWORD	`nonn`
	AUTHOR	`Michel Lagneau, Jan 18 2011`
	STATUS	`approved`

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Last modified May 19 07:18 EDT 2013. Contains 225429 sequences.