A179797 Numbers not of the form abc + abd + acd + bcd, with 0 < a < b < c < d.

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 73, 74, 75

Offset

1,2

Comments

This sequence appears to contain 764 terms, ending with 181799. Complement of A179796.

Links

T. D. Noe, Table of n, a(n) for n=1..764 (complete sequence)

MathOverflow, A generalisation of the equation n = ab + ac + bc

Mathematica

nn=1000000; lim=Floor[nn^(1/3)]; cnt=Table[0, {nn}]; Do[k1=a*b*c; k2=a*b+a*c+b*c; d=0; While[d++; n=k1+k2*d; n<=nn, If[d!=a && d!=b && d!=c, cnt[[n]]=1]], {a, lim}, {b, a+1, Floor[Sqrt[nn/a]]}, {c, b+1, Floor[nn/a/b]}]; Flatten[Position[cnt, 0]]

Crossrefs

Cf. A027563 (which allows equality)

Sequence in context: A357759 A120951 A272554 * A268200 A296873 A044923

Adjacent sequences: A179794 A179795 A179796 * A179798 A179799 A179800

Keyword

fini,full,nonn

Author

T. D. Noe, Aug 02 2010

Status

approved