The graceful pi-way is the path through the 15 states on the western and northern borders of the contiguous
USA graph, stretching from California to Maine, in a particular graceful
labeling. Its vertex labels are 31, 41, 59, 26, 53, 58, 97, 93, 23, 84, 62, 64,
33, 83, and 27, precisely the first 30 decimal digits of . T. Rokicki found the labeling in October 2020, and
Knuth (2025, p. 18) describes it as a "graceful miracle." With apologies
to Gordon Lightfoot's "Carefree Highway," the path
is illustrated in red above.
Graceful Pi-Way
See also
Contiguous USA Graph, Graceful Graph, Graceful Labeling, Pi DigitsExplore with Wolfram|Alpha
References
Knuth, D. E. §7.2.2.3 in The Art of Computer Programming, Vol. 4, Fascicle 7: Constraint Satisfaction. Boston, MA: Addison-Wesley, p. 18, 2025.Referenced on Wolfram|Alpha
Graceful Pi-WayCite this as:
Weisstein, Eric W. "Graceful Pi-Way." From MathWorld--A Wolfram Resource. https://mathworld.wolfram.com/GracefulPi-Way.html