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A173056 Numbers of the form a^b+b^a, a and b are primes. 1
8, 17, 54, 57, 177, 368, 2169, 2530, 6250, 8361, 94932, 131361, 178478, 524649, 1596520, 1647086, 8389137, 48989176, 129145076, 536871753, 1162268326, 1221074418, 1996813914, 2147484609, 94143190994, 96951758924, 137438954841 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

2^2+2^2=8, 2^3+3^2=17, 3^3+3^3=54, 2^5+5^2=57, 2^7+7^2=177, 3^5+5^3=368,..

LINKS

Table of n, a(n) for n=1..27.

MATHEMATICA

nMax=10^12; lim=PrimePi[Log[2, nMax]]; f[a_, b_]:=Prime[a]^Prime[b] + Prime[b]^Prime[a]; Select[Union[Flatten[Table[f[a, b], {a, lim}, {b, lim}]]], #<=nMax&]

nMax=10^12; lim=PrimePi[Log[2, nMax]]; Select[Union[First[#]^Last[#] + Last[#]^First[#]&/@ Tuples[Prime[Range[lim]], {2}]], #<=nMax&]  (* Harvey P. Dale, Mar 12 2011 *)

CROSSREFS

Cf. A076980, A173054, A173055.

Sequence in context: A329768 A153873 A111325 * A008782 A146078 A097058

Adjacent sequences:  A173053 A173054 A173055 * A173057 A173058 A173059

KEYWORD

nonn

AUTHOR

Vladimir Joseph Stephan Orlovsky, Feb 08 2010

STATUS

approved

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Last modified October 21 09:55 EDT 2021. Contains 348150 sequences. (Running on oeis4.)