cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A331463 Numbers k such that k and k + 1 are both binary hoax numbers (A329936).

Original entry on oeis.org

8, 15, 49, 50, 252, 489, 699, 725, 755, 799, 951, 979, 980, 988, 989, 1023, 1134, 1350, 1351, 1370, 1390, 1599, 1629, 1630, 1660, 1690, 1694, 1763, 1854, 1908, 1929, 1939, 1940, 1960, 2006, 2015, 2166, 2312, 2358, 2645, 2700, 2779, 2787, 2862, 2923, 2930, 2988
Offset: 1

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Author

Amiram Eldar, Jan 17 2020

Keywords

Examples

			8 is a term since both 8 and 8 + 1 = 9 are binary hoax numbers: 8 = 2^3 in binary representation is 1000 = 10^3 and 1 + 0 + 0 + 0 = 1 + 0, and 9 = 3^2 in binary representation is 1001 = 11^2 and 1 + 0 + 0 + 1 = 1 + 1.
		

Crossrefs

Programs

  • Magma
    hoax:=func; [k:k in [2..3000]|hoax(k) and hoax(k+1)]; // Marius A. Burtea, Jan 17 2020
  • Mathematica
    binWt[n_] := Total @ IntegerDigits[n, 2]; binHoaxQ[n_] := CompositeQ[n] && Total[binWt /@ FactorInteger[n][[;; , 1]]] == binWt[n]; seq = {}; isHoax1 = binHoaxQ[1]; Do[isHoax2 = binHoaxQ[n]; If[isHoax1 && isHoax2, AppendTo[seq, n-1]]; isHoax1 = isHoax2, {n, 2, 3000}]; seq