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A007960 Numbers n with property that some permutation of the digits of n is a triangular number. 1
1, 3, 6, 10, 12, 15, 19, 21, 28, 30, 36, 45, 51, 54, 55, 60, 63, 66, 78, 82, 87, 91, 100, 102, 105, 109, 117, 120, 123, 132, 135, 136, 147, 150, 153, 156, 163, 165, 168, 171, 174, 186, 190, 201, 208, 210, 213, 231, 235, 253, 258, 267, 276, 280, 285, 300, 306, 307 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Leading zeros may be omitted from the permutation of the digits of n to get T. But the number of digits of T must be <= the number of digits of n. - N. J. A. Sloane, Dec 14 2007

Working modulo 9, A010878(A000217(j)) is in the set {0, 1, 3, 6} for all j, never in {2, 4, 5, 7, 8}. Since permutation of decimal digits does not change values mod 9, A010878(n) is also one of {0,1,3,6}. - R. J. Mathar, Jan 08 2008

LINKS

Table of n, a(n) for n=1..58.

F. Smarandache, Only Problems, Not Solutions!

EXAMPLE

Contains n=1, n=10, n=100 etc. derived from T=1.

Contains n=3, n=30, n=300 etc. derived from T=3.

Contains n=15, n=51, n=105 and n=150 etc. derived from T=15.

CROSSREFS

Sequence in context: A114981 A319452 A187744 * A280243 A032732 A187352

Adjacent sequences:  A007957 A007958 A007959 * A007961 A007962 A007963

KEYWORD

nonn,base

AUTHOR

R. Muller

EXTENSIONS

Corrected a large number of errors, Apr 15 1996.

Edited, corrected and extended by R. J. Mathar, Jan 08 2008

STATUS

approved

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Last modified February 23 16:23 EST 2020. Contains 332177 sequences. (Running on oeis4.)