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A217920
Column 1 of A217916 (when formed into a number triangle).
2
2, 1, 2, 4, 2, 6, 6, 2, 6, 2, 6, 14, 4, 12, 6, 2, 4, 4, 2, 2, 6, 6, 2, 4, 6, 8, 6, 16, 6, 4, 6, 6, 6, 6, 6, 6, 14, 6, 6, 14, 10, 10, 8, 4, 12, 20, 8, 12, 6, 10, 2, 6, 14, 2, 14, 18, 6, 2, 6, 12, 4, 28, 6, 20, 6, 6, 6, 4, 16, 2, 2, 6, 4, 12, 6, 6, 6, 6, 8, 4, 6, 8, 6
OFFSET
1,1
COMMENTS
The number 2 appears in A217916 only in column 1.
The positions of 2 are given by A217919.
LINKS
FORMULA
a(n) = prime(n*(n-1)/2 + 1) - prime(n*(n-1)/2) for n>1 with a(1)=2.
CROSSREFS
KEYWORD
nonn
AUTHOR
Paul D. Hanna, Mar 04 2013
STATUS
approved