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A136402
Prime Wedderburn-Etherington numbers.
0
2, 3, 11, 23, 983, 2179, 24631, 3626149, 253450711, 596572387, 4958179972866730572551, 17950473826186485808766524097, 17690812163571687513245304152178763697755384812733, 9852801774222802457119814738073136914072348071335480633169417277909155746150705781482843
OFFSET
1,1
COMMENTS
Corresponding indices are 4, 5, 7, 8, 13, 14, 17, 23, 28, 29, 63, 80, 134, 233, 534, 732, 1963, 3896, 7792, 7987, 8312, ... with no more up to 2*10^4. - Charles R Greathouse IV, Mar 23 2014
Next index which produces a prime is 48979. - Robert G. Wilson v, May 21 2014
MATHEMATICA
a[n_?OddQ] := a[n] = Sum[a[k]*a[n - k], {k, 1, (n - 1)/2}]; a[n_?EvenQ] := a[n] = Sum[a[k]*a[n - k], {k, 1, n/2 - 1}] + (1/2)*a[n/2]*(1 + a[n/2]); a[0] = 0; a[1] = 1; Select[a@# & /@ Range@ 300, PrimeQ@# &] (* Robert G. Wilson v, May 20 2014, after Jean-François Alcover in A001190 *)
CROSSREFS
Cf. A001190.
Sequence in context: A363141 A374914 A065849 * A137811 A041955 A239445
KEYWORD
nonn
AUTHOR
STATUS
approved