A096489 - OEIS

A096489

Noncomposite numbers n such that number of decimal digits of n = number of divisors of n.

1, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97

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OFFSET

1,2

COMMENTS

Only 1 and primes with 2 decimal digits are here, so the sequence is finite: it consists of 1+25-4=22 terms. Part of A008364. Consists of the terms below 100 from A095862.

LINKS

Table of n, a(n) for n=1..22.

MATHEMATICA

{u=1, ta=Table[0, {25}]}; Do[s=Apply[Plus, IntegerDigits[n]]; s1=Length[IntegerDigits[n]]; If[Equal[s1, DivisorSigma[0, n]], Print[n]; ta[[u]]=n; u=u+1], {n, 1, 100}]

Select[Range[100], !CompositeQ[#]&&DivisorSigma[0, #]==IntegerLength[#]&] (* Harvey P. Dale, Jan 29 2024 *)

PROG

(PARI) print1(1); forprime(p=9, 99, print1(", "p)) \\ Charles R Greathouse IV, Apr 27, 2011

CROSSREFS

Cf. A008364, A095862.

Sequence in context: A063193 A056758 A322273 * A008364 A140461 A120533

Adjacent sequences: A096486 A096487 A096488 * A096490 A096491 A096492

KEYWORD

base,fini,full,nonn,easy

AUTHOR

Labos Elemer, Jun 25 2004

STATUS

approved