A255917 Triangular numbers n such that each decimal digit of n is equal to the difference of at least two other digits of n.

990, 3003, 5050, 10011, 10878, 13203, 15051, 28680, 39903, 41041, 45150, 64620, 66066, 81810, 93096, 107880, 108811, 145530, 155403, 165600, 191890, 203203, 237705, 322003, 339900, 404550, 405450, 414505, 441330, 468028, 499500, 500500, 502503, 504510

Offset

1,1

Comments

Proper subset of A255966. - Michel Marcus , Mar 13, 2015.

Links

Table of n, a(n) for n=1..34.

Example

10878 is in this sequence since it is the 147th triangular number and 1 = 8-7, 0 = 8-8, 8 = 8-0, 7 = 8-1 and 8 = 8-0, where the eights are different digits.

Mathematica

fQ[n_] := Block[{id = IntegerDigits@ n, lng = 1 + Floor@ Log10@ n}, Union@ Table[c = Complement[ Range@ lng, {i}]; MemberQ[ Union@ Flatten@ Table[Abs[id[[j]] - id[[k]]], {j, c}, {k, c}], id[[i]]], {i, lng}] == {True}]; tri[n_] := n(n + 1)/2; Select[ tri@ Range@ 1050, fQ]

Crossrefs

Cf. A000217, A255892, A255893.

Sequence in context: A224565 A341604 A295768 * A154071 A218133 A295433

Adjacent sequences: A255914 A255915 A255916 * A255918 A255919 A255920

Keyword

base,easy,nonn

Author

Michel Lagneau and Robert G. Wilson v, Mar 11 2015

Status

approved