OFFSET
1,3
COMMENTS
153, 370, 371, and 407 are well known with regard to the cubic numbers.
EXAMPLE
The octahedral numbers are represented by the formula, y(x)=(2x^3+x)/3; apply this formula to each of the digits in a(18)=739, i.e., y(7)=231, y(3)=19, y(9)=489; sum=739; the dodecahedral numbers are represented by the formula, y(x)=x(3x-1)(3x-2)/2; apply this formula to each of the digits in a(34)=9898, i.e., y(9)=2725, y(8)=2024; y(9)=2725, y(8)=2024; sum=9898.
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Thomas S. Pedigo, Nov 01 2012
STATUS
approved