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A069699
Triangular numbers with internal digits 7.
0
0, 1, 3, 6, 10, 15, 21, 28, 36, 45, 55, 66, 78, 91, 171, 276, 378, 1770, 2775, 5778, 8778
OFFSET
1,3
COMMENTS
For proof of finiteness see A069693.
MATHEMATICA
Do[ If[ Union[ Drop[ RotateLeft[ IntegerDigits[n(n + 1)/2]], -2]] == {6}, Print[n(n + 1)/2]], {n, 14, 2 10^6}]
CROSSREFS
KEYWORD
nonn,base,fini,full
AUTHOR
Amarnath Murthy, Apr 06 2002
EXTENSIONS
Corrected by Sascha Kurz, Jan 02 2003
STATUS
approved