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A331194 Numbers whose last digit is the number of their distinct prime factors. 0
11, 12, 22, 31, 41, 52, 61, 62, 71, 72, 81, 82, 92, 101, 112, 121, 122, 131, 142, 151, 152, 162, 172, 181, 191, 192, 202, 211, 212, 232, 241, 242, 251, 262, 271, 272, 273, 281, 292, 302, 311, 331, 332, 352, 361, 362, 382, 392 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

All prime numbers whose last digit is 1 have this property.

Only numbers with at most 9 distinct prime factors appear in this sequence.

LINKS

Table of n, a(n) for n=1..48.

EXAMPLE

272 is such a number because 272 = 2^4 * 17. It has 2 distinct prime factors {2,17} and its last digit is 2.

MATHEMATICA

Select[Range@500, Last@IntegerDigits@#==PrimeNu@#&]

PROG

(PARI) isok(m) = omega(m) == (m % 10); \\ Michel Marcus, Feb 24 2020

CROSSREFS

Cf. A001221 (omega), A010879 (final digit of n).

Sequence in context: A118512 A112651 A215027 * A105945 A139114 A022101

Adjacent sequences:  A331191 A331192 A331193 * A331195 A331196 A331197

KEYWORD

nonn,base

AUTHOR

Giorgos Kalogeropoulos, Feb 23 2020

STATUS

approved

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Last modified May 6 09:45 EDT 2021. Contains 343580 sequences. (Running on oeis4.)