1,1

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

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

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

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

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

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

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

nonn,base

Giorgos Kalogeropoulos, Feb 23 2020

approved