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A103125 4-Smith numbers. 2
2401, 5010, 7000, 10005, 10311, 10410, 10411, 11060, 11102, 11203, 12103, 13002, 13021, 13101, 14001, 14101, 14210, 20022, 20121, 20203, 20401, 21103, 21112, 21120, 21201, 22040, 22101, 22201, 23030, 30003, 30031, 30320, 31002, 31101 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,1
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000 (terms 1..600 from Harvey P. Dale)
Shyam Sunder Gupta, Smith Numbers.
Wayne L. McDaniel, The Existence of infinitely Many k-Smith numbers, Fibonacci Quarterly, Vol. 25, No. 1 (1987), pp. 76-80.
EXAMPLE
2401 is a 4-Smith number because the sum of the digits of its prime factors, i.e., Sp(2401) = Sp(7*7*7*7) = 7 + 7 + 7 + 7 = 28, which is equal to 4 times the digit sum of 2401, i.e., 4*S(2401) = 4*(2 + 4 + 0 + 1) = 28.
MATHEMATICA
sn4Q[n_]:=Module[{a=Total[Flatten[IntegerDigits/@(Table[First[#], {Last[ #]}]&/@FactorInteger[n])]], b=4Total[IntegerDigits[n]]}, a==b] (* Harvey P. Dale, Oct 03 2011 *)
CROSSREFS
Cf. A006753.
Sequence in context: A186488 A186487 A043396 * A074384 A016924 A016984
KEYWORD
base,nonn
AUTHOR
Shyam Sunder Gupta, Mar 16 2005
STATUS
approved

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Last modified February 21 03:13 EST 2024. Contains 370219 sequences. (Running on oeis4.)