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 A109886 Index of first occurrence of n in A109883, or -1 if n does not occur in A109883. 2
 1, 2, 3, 30, 5, 9, 7, 50, 20, 42, 11, 36, 13, 6510, 27, 54, 17, 70620, 19, 25, 46, 66, 23, 168630, 124, 98, 58, 78, 29 (list; graph; refs; listen; history; text; internal format)
 OFFSET 0,2 COMMENTS Sequence continues: a(30)=??, 31, 70, 112, 100, 57, 200, 37, 484, 55, 102, 41, 49, 43, a(44)=??, 94, 114, 47, 225, 1264, 252, 104, 294, 53, 780, 87, 71940, 118, 138, 59, 4290, 61, 1470, 85, 306, 134, a(66)=??, 67, 6300, 142, 288, 71, 324, 73, a(74)=??, 712, 174, 158, 2940, 79, a(80)=??, 166, 186, 83, 1344210, 405, 242, 115, 1590, 89, a(90)=??, 141, 196, 406, 540, 119, 2310, 97, 390, 202, 222, ..., . - Jason Earls and Robert G. Wilson v, Jul 12 2005 Smallest number N with perfect deficiency n, that is, the first number such that A109883(N)=n. - Walter Kehowski, Sep 13 2005 LINKS EXAMPLE a(7) = 50: divisors of 50 are 1,2,5,10,25,50; 50 - (1 + 2 + 5 + 10 + 25) = 7 and 50 is the smallest such number. MAPLE with(numtheory); pdef := proc(n) local k, d, divd; d:=n; divd:=sort([op(divisors(n))]); for k in divd while d>=k do d:=d-k; od; end: PDL:=[]; for z from 1 to 1 do for pd from 0 to 60 do for n from 1 to 200000 do missed:=true; if pdef(n)=pd then PDL:=[op(PDL), n]; missed:=false; break fi od; if missed then PDL:=[op(PDL), -1] fi od od; PDL; # Walter Kehowski, Sep 13 2005 MATHEMATICA subtract = If[ #1 < #2, Throw[ #1], #1 - #2]&; f[n_] := Catch @ Fold[subtract, n, Divisors @ n] (* Bobby R. Treat, (DrBob(AT)bigfoot.com), Jul 14 2005 *) t = Table[0, {60}]; Do[ a = f[n]; If[a < 60 && t[[a + 1]] == 0, t[[a + 1]] = n], {n, 10^8}] (* Robert G. Wilson v, Jul 14 2005 *) CROSSREFS Cf. A064510, A109883, A109884. Sequence in context: A078727 A270550 A076977 * A277811 A127615 A210417 Adjacent sequences:  A109883 A109884 A109885 * A109887 A109888 A109889 KEYWORD nonn AUTHOR Amarnath Murthy, Jul 11 2005 EXTENSIONS Corrected and extended by Jason Earls, Jul 12 2005 More terms from Walter Kehowski, Sep 13 2005 STATUS approved

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Last modified December 13 17:24 EST 2018. Contains 318086 sequences. (Running on oeis4.)