, Algorithm 1 can be called several times on sub-intervals of n + k ? [L/10, L ? 1], since the main memory usage (the sieve array T ) is proportional to the subinterval length. We used this for n = 44, 494, and 539, with sub-intervals of length 2 · 10 12 . And by storing only even values of T, ? If memory is a bottleneck

, Algorithm 1 was implemented in the C language, using the GMP library for the large integer operations, and OpenMP for the parallel code. The locks for accesses to T use the OpenMP atomic update instruction. On a processor with 112 hyperthreaded cores, this implementation takes about 100 seconds (of wall-clock time) to find C(98) = 259110640 with L = 10 9

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, Mathematics Subject Classification: 11B83 (11D72, 11D85) Keywords: Number sequences, Recamán sequence, recurrences, triangular number triples