A254956 Zeroless numbers n with digits d_1, d_2, ..., d_k such that d_1*(d_1+1)/2 + ... + d_k*(d_k+1)/2 is a triangular number.

1, 2, 3, 4, 5, 6, 7, 8, 9, 22, 35, 49, 53, 56, 65, 69, 94, 96, 111, 123, 132, 136, 144, 163, 199, 213, 225, 231, 233, 238, 245, 252, 254, 266, 283, 312, 316, 321, 323, 328, 332, 355, 359, 361, 367, 376, 382, 388, 395, 414, 425, 441, 452, 477, 489, 498, 522, 524, 535, 539, 542, 553, 555, 558, 585, 593, 599, 613, 626, 631

Offset

1,2

Comments

Any one of these terms can have an arbitrary number of 0's in between any two digits. Thus, the numbers with 0's have been omitted as trivial.

Links

Table of n, a(n) for n=1..70.

Prog

(PARI) istri(n)=for(k=0, n+1, if(k*(k+1)/2==n, return(1))); 0
for(n=1, 10^3, d=digits(n); if(vecsort(d, , 8)[1], s=0; for(i=1, #d, s+=d[i]*(d[i]+1)/2); if(istri(s), print1(n, ", "))))

Crossrefs

Cf. A000217.

Sequence in context: A274126 A108194 A083158 * A061013 A037264 A274124

Adjacent sequences: A254953 A254954 A254955 * A254957 A254958 A254959

Keyword

nonn,base

Author

Derek Orr, Feb 11 2015

Status

approved