A078256 Triangular numbers in which frequency of occurrence of every digit is same.
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 105, 120, 136, 153, 190, 210, 231, 253, 276, 325, 351, 378, 406, 435, 465, 496, 528, 561, 630, 666, 703, 741, 780, 820, 861, 903, 946, 1035, 1275, 1326, 1378, 1485, 1540, 1596, 1653, 1830, 1953, 2016, 2145
Offset: 1
Links
- Andrew Howroyd, Table of n, a(n) for n = 1..10000
Programs
-
Mathematica
T[n_] := n*(n + 1)/2;f[n_] := Block[{dc = DigitCount[n], s},s = Select[dc, Positive];Min @@ s == Max @@ s];Select[Array[T, 70, 0], f] (* Ray Chandler, May 11 2007 *) -
PARI
\\ here isok(k) tests if each digit k has equal frequency. isok(k)={my(f=vector(10)); foreach(digits(k), t, f[1+t]++); my(c=vecmax(f)); 0==#select(t->t>0&&t
Extensions
Offset changed by Andrew Howroyd, Sep 21 2024