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 A254671 Numbers that can be represented as x * y + x + y, where x >= y > 1. 7
 8, 11, 14, 15, 17, 19, 20, 23, 24, 26, 27, 29, 31, 32, 34, 35, 38, 39, 41, 43, 44, 47, 48, 49, 50, 51, 53, 54, 55, 56, 59, 62, 63, 64, 65, 67, 68, 69, 71, 74, 75, 76, 77, 79, 80, 83, 84, 86, 87, 89, 90, 91, 92, 94, 95, 97, 98, 99, 101, 103, 104, 107, 109, 110, 111, 113 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Apparently 8 and the elements of A061743. - R. J. Mathar, Feb 19 2015 LINKS Table of n, a(n) for n=1..66. EXAMPLE 14 = 2 * 4 + 2 + 4. 15 = 3 * 3 + 3 + 3. There is no way to express 16 in this form, so it is not in the sequence. MATHEMATICA sol[t_] := Solve[x >= y > 1 && x y + x + y == t, {x, y}, Integers]; Select[Range[200], sol[#] != {}&] (* Jean-François Alcover, Jul 28 2020 *) PROG (Python) def aupto(limit): cands = range(2, limit//3+1) nums = [x*y+x+y for i, y in enumerate(cands) for x in cands[i:]] return sorted(set(k for k in nums if k <= limit)) print(aupto(113)) # Michael S. Branicky, Aug 11 2021 CROSSREFS Cf. A254636 is the complement. Sequence in context: A106670 A247463 A308562 * A265412 A372498 A345488 Adjacent sequences: A254668 A254669 A254670 * A254672 A254673 A254674 KEYWORD nonn AUTHOR Alex Ratushnyak, Feb 04 2015 STATUS approved

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Last modified August 8 16:21 EDT 2024. Contains 375023 sequences. (Running on oeis4.)