

A213671


The odd part of n^2  n + 2.


3



1, 1, 1, 7, 11, 1, 11, 29, 37, 23, 7, 67, 79, 23, 53, 121, 137, 77, 43, 191, 211, 29, 127, 277, 301, 163, 11, 379, 407, 109, 233, 497, 529, 281, 149, 631, 667, 11, 371, 781, 821, 431, 113, 947, 991, 259, 541, 1129, 1177, 613, 319, 1327, 1379, 179
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OFFSET

1,4


COMMENTS

The first composite term s of this sequence which is not multiple of a prime term appeared before s is a(245) = 29891 = 71*421  neither of 71, 421 are terms before a(245).  Peter J. C. Moses, Mar 03 2013
The probability that n points uniformly distributed in (or on) a sphere are in the same hemisphere is (n^2n+2)/2^n, for which this is the numerator.  Charles R Greathouse IV, Sep 18 2013


LINKS

Table of n, a(n) for n=1..54.


FORMULA

a(n) = A000265(n^2n+2).  R. J. Mathar, Mar 10 2013


MAPLE

A213671 := proc(n)
A000265(n^2n+2) ;
end proc: # R. J. Mathar, Mar 10 2013


MATHEMATICA

Table[k = n^2  n + 2; k/2^IntegerExponent[k, 2], {n, 100}] (* T. D. Noe, Mar 16 2013 *)


PROG

(PARI) a(n)=n=n^2n+2; n>>valuation(n, 2) \\ Charles R Greathouse IV, Sep 18 2013


CROSSREFS

Sequence in context: A091920 A036934 A070421 * A050081 A144076 A113492
Adjacent sequences: A213668 A213669 A213670 * A213672 A213673 A213674


KEYWORD

nonn,easy


AUTHOR

Vladimir Shevelev, Mar 03 2013


STATUS

approved



