A355036 a(n) is the least number whose product of digits in primorial base equals n.
0, 1, 5, 21, 17, 159, 23, 1509, 29, 111, 161, 25659, 83, 392949, 1511, 171, 89, 8711259, 113, 184837209, 167, 1521, 25661, 5141378799, 119, 1209, 392951, 741, 1517, 187854439329, 173, 6224078222919, 149, 25671, 8711261, 1629, 203, 274774574506989, 184837211
Offset: 0
Examples
The first terms, alongside their primorial base expansion, are: n a(n) pr(a(n)) -- --------- ------------------ 0 0 0 1 1 1 2 5 2_1 3 21 3_1_1 4 17 2_2_1 5 159 5_1_1_1 6 23 3_2_1 7 1509 7_1_1_1_1 8 29 4_2_1 9 111 3_3_1_1 10 161 5_1_2_1 11 25659 11_1_1_1_1_1 12 83 2_3_2_1 13 392949 13_1_1_1_1_1_1
Links
Programs
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PARI
a(n) = { if (n==0, 0, my (v=0, f=1); forprime (r=2, oo, forstep (d=r-1, 1, -1, if (n%d==0, v+=f*d; n/=d; break;);); if (n==1, return (v), f*=r))) }
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