A380375 Delete all 0's from n, then replace each remaining digit k of n by A000005(k).

1, 2, 2, 3, 2, 4, 2, 4, 3, 1, 11, 12, 12, 13, 12, 14, 12, 14, 13, 2, 21, 22, 22, 23, 22, 24, 22, 24, 23, 2, 21, 22, 22, 23, 22, 24, 22, 24, 23, 3, 31, 32, 32, 33, 32, 34, 32, 34, 33, 2, 21, 22, 22, 23, 22, 24, 22, 24, 23, 4, 41, 42, 42, 43, 42, 44, 42, 44, 43, 2, 21, 22, 22, 23, 22, 24, 22, 24, 23

Offset

1,2

Comments

Numbers including only the digits 1,2,3,4.

Links

John Tyler Rascoe, Table of n, a(n) for n = 1..10000

Formula

a(10^n) = 1.

Example

n = 10: delete 0, replace digit 1 by A000005(1), thus a(10) = 1.
n = 24: replace digit 2 by A000005(2), replace digit 3 by A000005(3), thus a(22) = 22.

Mathematica

a[n_] := FromDigits[DivisorSigma[0, DeleteCases[IntegerDigits[n], 0]]]; Array[a, 100] (* Amiram Eldar, Jan 23 2025 *)

Prog

(Python)
def A380375(n):
    d, y = [1, 2, 2, 3, 2, 4, 2, 4, 3], ""
    for i in str(n).replace("0", ""):
        y += str(d[int(i)-1])
    return int(y) # John Tyler Rascoe, Feb 27 2025

Crossrefs

Cf. A000005, A004719.

Sequence in context: A341946 A339915 A306509 * A083867 A076888 A357171

Adjacent sequences: A380372 A380373 A380374 * A380376 A380377 A380378

Keyword

nonn,base

Author

Ctibor O. Zizka, Jan 23 2025

Status

approved