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A231115 Start with 1; then a(n+1) = concatenation of c(d) and d*c(d), where d is the last digit of a(n) and the counter c(d) is increased at each occurrence of d, and once more if d*c(d) would end in zero. 0
1, 11, 22, 12, 24, 14, 28, 18, 216, 16, 212, 36, 318, 324, 312, 48, 432, 612, 714, 416, 424, 624, 728, 648, 756, 636, 742, 816, 848, 864, 832, 918, 972, 1122, 1224, 936, 954, 1144, 1248, 1188, 1296, 1166, 1272, 1326, 1378, 13104, 1352, 1428 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
COMMENTS
The resulting sequence shows the multiplications that have been done, where the "," becomes the multiplication operator. E.g., ...,312,48,... shows that at this point the digit '2' occurred for the 4th time and the calculation was 2*4=8. At the next occurrence one would get 2 x 5 = 10 which is forbidden, so the counter is set to 6, which yields the 432,612 <=> 2*6=12.
LINKS
E. Angelini, Concatenating multiplications and successive results, post to SeqFan list, Nov 04 2013
PROG
(PARI) c=vector(9); a=1; for(n=1, 99, print1(a", "); d=a%10; until(P%10, P=d*c[d]++); a=eval(Str(c[d], P)))
CROSSREFS
Sequence in context: A064263 A138838 A139337 * A040110 A140452 A048136
KEYWORD
nonn,base
AUTHOR
Eric Angelini and M. F. Hasler, Nov 04 2013
STATUS
approved

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Last modified May 23 17:39 EDT 2024. Contains 372765 sequences. (Running on oeis4.)