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A335120 The prime terms of A225563. 0
3, 5, 7, 11, 13, 17, 31, 41, 61, 97, 103, 137, 193, 241, 257, 409, 641, 769, 1021, 1361, 1543, 5441, 6529, 7681, 8161, 12289, 15361, 17477, 26113, 30841, 40961, 43691, 61441, 61681, 65537, 82241, 87041, 98689, 131071, 163841, 174761, 328961, 417793, 557057, 786433 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Apparently, the prime terms of A225563 are relatively rare. For example, of the first 10^4 terms of A225563, only 23 are primes.

LINKS

Table of n, a(n) for n=1..45.

MATHEMATICA

totQ[n_] := PrimeQ[n] && Module[{it = Most@FixedPointList[EulerPhi, n], sum, x}, sum = Plus @@ it; If[OddQ[sum], False, CoefficientList[Product[1 + x^i, {i, it}], x][[1 +sum/2]] > 0]]; Select[Range[10^3], totQ]

CROSSREFS

Cf. A225563.

Sequence in context: A228118 A136186 A023210 * A153601 A153602 A136187

Adjacent sequences:  A335117 A335118 A335119 * A335121 A335122 A335123

KEYWORD

nonn

AUTHOR

Amiram Eldar, May 24 2020

STATUS

approved

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Last modified June 14 00:02 EDT 2021. Contains 345016 sequences. (Running on oeis4.)