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A076406
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Numbers whose digital sum is equal to the sum of primes from their smallest to largest prime factor.
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0
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2, 3, 5, 7, 98, 640, 735, 980, 2401, 2625, 2744, 4913, 5145, 6272, 6400, 9800, 9856, 14336, 27440, 33614, 36015, 58564, 62720, 64000, 94325, 98000, 98560, 143360, 188650, 232925, 252105, 274400, 298144, 336140, 401408, 405769, 465850, 570999
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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EXAMPLE
| 980 = 2*2*5*7*7 is here since 9+8=17 and 2+3+5+7 = 17.
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MATHEMATICA
| okQ[n_]:=Module[{totidn=Total[IntegerDigits[n]], fctrs, mn, mx}, fctrs=Transpose[FactorInteger[n]][[1]]; mn=Min[fctrs]; mx=Max[fctrs]; Total[Prime[Range[PrimePi[mn], PrimePi[mx]]]]==totidn];
Select[Range[2, 10000], okQ]
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CROSSREFS
| Sequence in context: A070275 A171042 A068827 * A171050 A092909 A080437
Adjacent sequences: A076403 A076404 A076405 * A076407 A076408 A076409
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KEYWORD
| base,nonn
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AUTHOR
| Jason Earls (zevi_35711(AT)yahoo.com), Nov 07 2002
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EXTENSIONS
| a(20)-a(38) from Donovan Johnson (donovan.johnson(AT)yahoo.com), Sep 24 2009
Mathematica program provided by Harvey P. Dale.
Mathematica program adjusted to not step through 1 and trigger Prime[0] error; and also upper bound lowered so as to give an answer more quickly (this program takes a few minutes to go all the way up to 600000).
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