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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

Harvey P. Dale, Table of n, a(n) for n = 1..600

S. S. Gupta, Smith Numbers.

W. L. McDaniel, The Existence of infinitely Many k-Smith numbers, Fibonacci Quarterly, 25(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

Adjacent sequences:  A103122 A103123 A103124 * A103126 A103127 A103128

KEYWORD

base,nonn

AUTHOR

Shyam Sunder Gupta, Mar 16 2005

STATUS

approved

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Last modified June 26 14:42 EDT 2017. Contains 288766 sequences.