A247095 Smallest number m such that A250030(m) = n.

8, 7, 6, 14, 13, 30, 29, 157, 317, 626, 3095, 6637, 26833, 145687, 461938, 1068037, 16007153, 54690697, 246107086, 328144133

Offset

1,1

Comments

a(21) and all further terms > 10^9. - Michael S. Branicky, Sep 08 2025

Links

Table of n, a(n) for n=1..20.

Formula

A250030(a(n)) = n and A250030(m) != n for m < a(n).

Prog

(Haskell)
import Data.List (elemIndex); import Data.Maybe (fromJust)
a247095 = (+ 5) . fromJust . (`elemIndex` a250030_list)
(PARI) A008474(n) = my(f=factor(n)); sum(i=1, #f~, f[i, 1]+f[i, 2]);
f(n) = my(k=0); while(n!=5, n=A008474(n); k++); k; \\ A250030
a(n) = my(k=5); while(f(k) != n, k++); k; \\ Michel Marcus, Feb 05 2022
(Python)
from itertools import count, islice
from sympy import factorint
def f(n): # A250030
    k = 0
    while n != 5: n, k = sum(p+e for p, e in factorint(n).items()), k + 1
    return k
def agen(): # generator of terms
    adict, n = dict(), 1
    for k in count(5):
        v = f(k)
        if v not in adict:
            adict[v] = k
            while n in adict: yield adict[n]; n += 1
print(list(islice(agen(), 16))) # Michael S. Branicky, Sep 08 2025

Crossrefs

Cf. A008474, A250030.

Sequence in context: A393964 A124597 A347903 * A214023 A393498 A154209

Adjacent sequences: A247092 A247093 A247094 * A247096 A247097 A247098

Keyword

nonn,more

Author

Reinhard Zumkeller, Nov 18 2014

Extensions

a(17)-a(18) from Michel Marcus, Feb 05 2022

a(4) corrected and a(19)-a(20) from Michael S. Branicky, Sep 08 2025

Status

approved