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A307330 Indices of Ulam prime triples, where u(k), u(k+1) and u(k+2) are all primes, and u(k) = A002858(k) are the Ulam numbers. 0
858, 1547, 2515, 3059, 9503, 9781, 11899, 11900, 13622, 15413, 18928, 22829, 25462, 32020, 33021, 33963, 36598, 37811, 37854, 40046, 44447, 49104, 55249, 56526, 60847, 61741, 80658, 84414, 86235, 87971, 92832, 96674, 97185, 100004, 102684, 108025, 108273 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..37.

MATHEMATICA

ulams = {1, 2}; Do[AppendTo[ulams, n = Last[ulams]; While[n++; Length[ DeleteCases[Intersection[ulams, n - ulams], n/2, 1, 1]] != 2]; n], {1000}]; p = PrimeQ[ulams]; len = Length[p]; s={}; Do[If[p[[n]]&&p[[n+1]]&&p[[n+2]], AppendTo[s, n]], {n, 1, len-2}]; s (* after Jean-Fran├žois Alcover at A002858 *)

CROSSREFS

Cf. A002858, A068820, A307328, A307329.

Sequence in context: A251453 A087002 A256743 * A046394 A163304 A252237

Adjacent sequences:  A307327 A307328 A307329 * A307331 A307332 A307333

KEYWORD

nonn

AUTHOR

Amiram Eldar, Apr 02 2019

STATUS

approved

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Last modified January 26 23:05 EST 2020. Contains 331289 sequences. (Running on oeis4.)