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A090873 a(n) is the smallest number m such that n^2^k + m^2^k is prime for k=0,1,2,3 and 4. 3
1, 1, 218368, 9324385, 6628674, 601, 365082, 532253, 449140, 4193407, 175746, 2857547, 2752708, 6315245, 80612, 3354745, 10892, 953, 6577504, 157437, 2247676, 11357637, 7650, 272935, 318784, 8034141, 1158380, 22315, 610550, 340357 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
LINKS
FORMULA
a[n_] := (For[m=1, !(PrimeQ[m+n]&&PrimeQ[m^2+n^2]&&PrimeQ[m^4+n^4]&& PrimeQ[m^8+n^8]&&PrimeQ[m^16+n^16]), m++ ];m)
EXAMPLE
a(2)=1 because 2^2^k + 1 is prime for k= 0,1,2,3 and 4.
MATHEMATICA
a[n_] := (For[m=1, !(PrimeQ[m+n]&&PrimeQ[m^2+n^2]&&PrimeQ[m^4+n^4]&& PrimeQ[m^8+n^8]&&PrimeQ[m^16+n^16]), m++ ]; m); Do[Print[a[n]], {n, 50}]
CROSSREFS
Sequence in context: A205915 A205907 A157377 * A236040 A251480 A072189
KEYWORD
nonn
AUTHOR
Farideh Firoozbakht, Feb 06 2004
STATUS
approved

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Last modified February 24 07:07 EST 2024. Contains 370294 sequences. (Running on oeis4.)