A247016 Triangular numbers A000217 composed of only curved digits {0, 2, 3, 5, 6, 8, 9}.

0, 3, 6, 28, 36, 55, 66, 253, 300, 325, 528, 595, 630, 666, 820, 903, 990, 2080, 2556, 2628, 2850, 2926, 3003, 3655, 3828, 5050, 5253, 5356, 5565, 5886, 5995, 6328, 6555, 6903, 8256, 8385, 20503, 22366, 23005, 23220, 23653, 25200, 26335, 26565, 28203, 28680, 28920

Offset: 1

Author

K. D. Bajpai, Sep 09 2014

Keywords

• nonn
• base
• less

Comments

Intersection of A000217 and A028374.

Examples

			a(10) = 528 is in the sequence because it is A000217(32) and composed of only curved digits 5, 2 and 8.
a(14) = 820 is in the sequence because it is A000217(40) and composed of only curved digits 8, 2 and 0.
		

Links

• K. D. Bajpai, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A000217, A028374, A034470, A072960.

Programs

Mathematica

A247016 = {}; Do[t = n*(n + 1)/2; If[Intersection[IntegerDigits[t], {1, 4, 7}] == {}, AppendTo[A247016, t]], {n,0, 500}]; A247016
Select[Accumulate[Range[0,300]],DigitCount[#,10,1]==DigitCount[#,10,4] == DigitCount[ #,10,7] == 0&] (* Harvey P. Dale, Apr 18 2019 *)

Python

for n in range(2,10**3):
  s = str(int(n*(n-1)/2))
  if not (s.count('1') + s.count('4') + s.count('7')):
    print(int(s),end=', ') # Derek Orr, Sep 18 2014

Extensions

Added starting number 0 (suggested by D. Orr), added A-number in the name and examples. - Wolfdieter Lang, Oct 06 2014