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jonesor/RiceOnAChessBoard.R

Last active July 18, 2026 20:17
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RiceOnAChessBoard.R
# Rice on a chessboard: 1 grain on the first square, doubling each square.
# Vectorised: square i holds 2^(i-1) grains.
RiceOnASquare <- 2^(0:63)
sum(RiceOnASquare)
# NOTE: the true total is 2^64 - 1 = 18,446,744,073,709,551,615, which exceeds
# R's exact double-precision integer range (2^53). For the exact value use gmp:
# library(gmp); sum(as.bigz(2)^(0:63))
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