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A109311 Numbers n such that sum of n-th and (n+1)-st semiprimes is a square=q^2. +0
2
6, 17, 58, 78, 89, 122, 187, 219, 229, 278, 313, 353, 367, 552, 589, 966, 1162, 1264, 1530, 1637, 1745, 1928, 2343, 2443, 2540 (list; graph; listen)
OFFSET

1,1

FORMULA

sp(n)+sp(n+1)=q^2, sp(n)=n-th semiprime.

EXAMPLE

6 is ok because sp(6)=15, sp(7)=21, 15+21=36=6^2, sp(n)=A001358(n)=n-th semiprime.

CROSSREFS

Values of q: A109312. Cf. A001358 = semiprimes, A092191 = numbers n such that sum of n-th and (n+1)-st semiprimes is a semiprime.

Sequence in context: A083334 A088016 A010330 this_sequence A006758 A123189 A047156

Adjacent sequences: A109308 A109309 A109310 this_sequence A109312 A109313 A109314

KEYWORD

nonn

AUTHOR

Zak Seidov (zakseidov(AT)yahoo.com), Jun 27 2005

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Last modified August 29 17:54 EDT 2008. Contains 143238 sequences.


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