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A280032 Composite numbers n such that the number of digits in n equals the total number of digits in the prime power factorization of n. 1
10, 14, 15, 16, 21, 25, 27, 32, 35, 49, 64, 81, 105, 106, 111, 112, 115, 118, 119, 121, 122, 123, 129, 133, 134, 135, 141, 142, 145, 146, 147, 155, 158, 159, 160, 161, 162, 166, 169, 175, 177, 178, 183, 185, 189, 192, 194, 201, 203, 205, 213, 215, 217, 219, 224, 235, 237, 245, 249, 250 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Suggested by A279070.

Primes are excluded by decree.

In the prime power factorization of p we write p rather than p^1.

LINKS

Vincenzo Librandi, Table of n, a(n) for n = 1..5100

EXAMPLE

10 = 2*5 is a term (both have 2 digits).

27 = 3^3 is a term (both have 2 digits).

MATHEMATICA

ndf[n_]:=Total[IntegerLength/@Select[Flatten[FactorInteger[n]], #!=1&]];

Select[Range[250], !PrimeQ[#]&&IntegerLength[#]==ndf[#]&] (* Ivan N. Ianakiev, Dec 28 2016 *)

CROSSREFS

Cf. A279070.

Sequence in context: A241041 A164936 A102361 * A227010 A246449 A121836

Adjacent sequences:  A280029 A280030 A280031 * A280033 A280034 A280035

KEYWORD

nonn,base

AUTHOR

N. J. A. Sloane, Dec 27 2016

EXTENSIONS

a(14)-a(60) from Ivan N. Ianakiev, Dec 28 2016

STATUS

approved

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Last modified October 18 12:18 EDT 2019. Contains 328160 sequences. (Running on oeis4.)