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A060676 Numbers n such that sigma (x) = n has exactly 12 solutions. 0
1512, 1872, 2352, 3192, 3780, 4104, 4560, 4752, 5880, 6120, 8160, 8424, 8820, 11424, 13056, 15264, 16464, 16704, 17160, 17360, 17760, 18648, 19680, 19800, 20880, 22752, 23616, 24552, 24864, 27432, 30336, 30492, 31200, 32448, 35328 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..35.

EXAMPLE

1512 = sigma(480) = sigma(636) = sigma(736) = sigma(748) = sigma(830) = sigma(902) = sigma(1006) = sigma(1105) = sigma(1255) = sigma(1391) = sigma(1411) = sigma(1511).

MATHEMATICA

a = Table[ 0, {50000} ]; Do[ s = DivisorSigma[ 1, n ]; If[ s < 50001, a[ [ s ] ]++ ], {n, 1, 50000} ]; Select[ Range[ 50000 ], a[ [ # ] ] == 12 & ]

Take[Sort[Transpose[Select[Tally[DivisorSigma[1, Range[100000]]], #[[2]] == 12&]][[1]]], 50] (* Harvey P. Dale, Jan 18 2013 *)

CROSSREFS

Cf. A007370, A007371, A007372.

Sequence in context: A237725 A200915 A298223 * A230402 A248718 A255334

Adjacent sequences:  A060673 A060674 A060675 * A060677 A060678 A060679

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Apr 18 2001

STATUS

approved

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Last modified October 15 18:26 EDT 2019. Contains 328037 sequences. (Running on oeis4.)