

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
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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

Table of n, a(n) for n=0..28.


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:=dk; 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



