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A033629 Numbers that are not the sum of two distinct Ulam numbers. 5
23, 25, 33, 35, 43, 45, 67, 92, 94, 96, 111, 121, 136, 143, 160, 165, 170, 172, 187, 194, 204, 226, 231, 248, 265, 270, 280, 287, 292, 297, 302, 304, 314, 331, 336, 346, 348, 353, 368, 380, 397, 407, 419, 424, 446, 463, 468, 473, 475, 480, 490, 495, 507 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

REFERENCES

R. K. Guy, Unsolved Problems in Number Theory, C4

LINKS

T. D. Noe, Table of n, a(n) for n=1..1000

Ivano Salvo, Agnese Pacifico, Computing Integer Sequences: Filtering vs Generation (Functional Pearl), arXiv:1807.11792 [cs.PL], 2018.

MATHEMATICA

terms = 1000; ulams = {1, 2};

Do[AppendTo[ulams, n = Last[ulams]; While[n++; Length[ DeleteCases[ Intersection[ ulams, n - ulams], n/2, 1, 1]] != 2]; n], {terms}];

uu = Total /@ Subsets[ulams, {2}] // Union;

Complement[Range[Last[uu]], uu] // Take[#, {3, terms+2}]& (* Jean-Fran├žois Alcover, Dec 02 2018 *)

CROSSREFS

Cf. A002858.

Sequence in context: A054795 A305469 A093805 * A090311 A172015 A112073

Adjacent sequences:  A033626 A033627 A033628 * A033630 A033631 A033632

KEYWORD

nonn

AUTHOR

Jud McCranie

STATUS

approved

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Last modified November 20 05:07 EST 2019. Contains 329323 sequences. (Running on oeis4.)