login
A249724
Numbers k such that on row k of Pascal's triangle there is no multiple of 9 which would be less than any (potential) multiple of 4 on the same row.
5
0, 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 14, 16, 17, 20, 22, 23, 24, 25, 26, 28, 30, 32, 33, 34, 35, 36, 38, 40, 41, 42, 44, 48, 49, 50, 51, 52, 53, 56, 57, 58, 60, 61, 62, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 76, 77, 78, 80, 84, 86, 88, 89, 92, 94, 96, 97, 98, 100, 101, 102, 104, 105, 106, 107, 108, 110, 112, 113, 114, 115, 116, 120, 121
OFFSET
1,3
COMMENTS
Disjoint union of {0} and the following sequences: A048278 (gives 7 other cases where there are neither multiples of 4 nor 9 on row k), A249722 (rows where a multiple of 4 is found before a multiple of 9), A249726 (cases where the least term on row k which is a multiple of 4 is also a multiple of 9, and vice versa, i.e., such a term a multiple of 36).
If A249717(k) < 3 then k is included in this sequence. This is a sufficient but not necessary condition, e.g., A249717(25) = 5, but 25 is also included in this sequence.
LINKS
PROG
(PARI)
A249724list(upto_n) = { my(i=0, n=0, dont_print=0); while(i<upto_n, for(k=0, n\2, if(!(binomial(n, k)%4), i++; write("b249724.txt", i, " ", n); dont_print=1; break, if(!(binomial(n, k)%9), dont_print=1; break))); if(!dont_print, i++; write("b249724.txt", i, " ", n), dont_print=0); n++); } \\ Ugly code.
KEYWORD
nonn
AUTHOR
Antti Karttunen, Nov 04 2014
STATUS
approved