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A019506 Hoax numbers: composite numbers whose digit-sum equals the sum of the digit-sums of its distinct prime factors. 19
22, 58, 84, 85, 94, 136, 160, 166, 202, 234, 250, 265, 274, 308, 319, 336, 346, 355, 361, 364, 382, 391, 424, 438, 454, 456, 476, 483, 516, 517, 526, 535, 562, 627, 634, 644, 645, 650, 654, 660, 663, 690, 702, 706, 732, 735, 762, 778, 855, 860 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Eric Weisstein's World of Mathematics, Hoax Number
FORMULA
A007953(a(n)) = sum(A007953(A027748(a(n),k)): k=1..A001221(a(n))) and A066247(a(n)) = 1. [Reinhard Zumkeller, Dec 19 2011]
EXAMPLE
22 = 2*11 and digit-sum(22) = 4 = digit-sum(2) + digit-sum(11).
MATHEMATICA
Select[Range[2, 1000], !PrimeQ[#]&&Total[Flatten[IntegerDigits/@ Transpose[ FactorInteger[#]][[1]]]]==Total[IntegerDigits[#]]&] (* Harvey P. Dale, Feb 24 2013 *)
PROG
(Haskell)
a019506 n = a019506_list !! (n-1)
a019506_list = [x | x <- a002808_list,
a007953 x == sum (map a007953 (a027748_row x))]
-- Reinhard Zumkeller, Dec 19 2011
(PARI) isok(m) = !isprime(m) && (sumdigits(m) == vecsum(apply(sumdigits, factor(m)[, 1]))); \\ Michel Marcus, Feb 03 2022
CROSSREFS
Cf. A006753.
Sequence in context: A088820 A058097 A131878 * A202387 A044124 A044505
KEYWORD
nonn,base
AUTHOR
Mario Velucchi (mathchess(AT)velucchi.it)
STATUS
approved

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Last modified May 22 06:48 EDT 2024. Contains 372743 sequences. (Running on oeis4.)