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 A002784 A problem in parity. (Formerly M0401 N0154) 1
 1, 1, 1, 2, 3, 1, 1, 4, 5, 1, 3, 1, 3, 1, 1, 8, 15, 3, 7, 4, 5, 2, 3, 3, 6, 2, 3, 2, 3, 1, 1, 16, 19, 7, 10, 5, 15, 4, 5, 7, 15, 3, 7, 4, 5, 2, 3, 5, 13, 3, 5, 4, 7, 1, 3, 3, 5, 2, 3, 1, 3, 1, 1, 32, 47, 11, 31, 14, 21, 6, 15, 11, 31, 7, 9, 7, 12, 3, 7, 12, 21, 7, 15, 4, 11, 4, 5, 7, 15, 2, 7, 4, 5 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,4 REFERENCES H. Gupta, On a problem in parity, Indian J. Math., 11 (1969), 157-163. MR0260659 N. J. A. Sloane, A Handbook of Integer Sequences, Academic Press, 1973 (includes this sequence). N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS H. Gupta, On a problem in parity, Indian J. Math., 11 (1969), 157-163. [Annotated scanned copy] PROG (PARI) a(n)=if(n<1, 0, sum(k=1, n, if(gcd(n, k) == 1, ((n+k-1)!/(n!*k!))%2))) CROSSREFS Cf. A050169, A073166. Sequence in context: A214690 A238878 A011249 * A276010 A166029 A049278 Adjacent sequences:  A002781 A002782 A002783 * A002785 A002786 A002787 KEYWORD nonn AUTHOR EXTENSIONS PARI code and more terms from Michael Somos, Jul 19 2002 STATUS approved

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Last modified February 19 00:54 EST 2020. Contains 332028 sequences. (Running on oeis4.)