OFFSET
1,2
COMMENTS
Number of symmetric foldings of a strip of <= n stamps. The subsequence of primes begins 3, 5, 23, 41, 61, 1049, 1412351.
FORMULA
a(n) = SUM[i=1..n] A001010(i).
EXAMPLE
a(13) = 1 + 2 + 2 + 4 + 6 + 8 + 18 + 20 + 56 + 48 + 178 + 132 + 574 = 1049 is prime.
CROSSREFS
KEYWORD
nonn
AUTHOR
Jonathan Vos Post, Dec 31 2010
STATUS
approved