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A131697 Prime averages of two successive perfect prime powers. 1
101, 577, 677, 2203, 15877, 22501, 25609, 32401, 42061, 57601, 72901, 181501, 228211, 324901, 378229, 394393, 462409, 695581, 804709, 1664101, 1742401, 1971241, 2873029, 3062509, 3186229, 4137181, 4305661, 4347229, 4804889, 5336101, 6200269, 6502501, 7177693, 7209229 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
EXAMPLE
101 is the average of 81 and 121.
MATHEMATICA
a = Select[ Range[2, 10000000], ! PrimeQ[ # ] && Length[FactorInteger[ # ]] == 1 &]; sizea = Length[a]; (a[[Select[Range[sizea - 1], PrimeQ[(a[[ # ]] + a[[ # + 1]])/2] &]]] + a[[Select[Range[sizea - 1], PrimeQ[(a[[ # ]] + a[[ # + 1]])/2] &] + 1]])/2
CROSSREFS
Cf. A000961, A075455 (Prime averages of two successive perfect powers).
Sequence in context: A142692 A060012 A142507 * A153806 A227521 A364147
KEYWORD
nonn
AUTHOR
Tanya Khovanova, Sep 15 2007
EXTENSIONS
More terms from Amiram Eldar, Feb 18 2022
STATUS
approved

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Last modified June 23 17:30 EDT 2024. Contains 373653 sequences. (Running on oeis4.)