A249714 Record values in A249695.

0, 1, 3, 6, 7, 12, 21, 24, 48, 96, 192, 384, 768, 1536, 3072, 6144, 12288, 24576, 49152, 98304, 196608, 393216, 786432, 1572864, 3145728, 6291456, 12582912, 25165824, 50331648

Offset: 1

Author

Charles R Greathouse IV & Antti Karttunen, Nov 04 2014

Keywords

• nonn

Comments

For n >= 8 [a(8) = 24], the terms seem to be given by A007283(n-5), i.e. as 3 * 2^(n-5).

Crossrefs

A249715 gives the positions where these values occur in A249695 for the first time.

Cf. A007283, A249439.

Programs

PARI

A249695(n) = { for(p=2,3,for(k=0,floor(n/2),if((0==(binomial(n,k)%(p*p))),return(k)))); return(0); } \\ Unoptimized and straightforward.
A249695(n) = { for(p=2,3, my(o=0); for(k=1, n\2, o+=valuation((n-k+1)/k, p); if(o>1, return(k)))); return(0); } \\ Better to use this. Based on Charles R Greathouse IV's PARI-code for A249441.
prevmax = -1; i = 0; for(n=0, 123456789, if((k=A249695(n)) > prevmax, prevmax = k; i++; write("b249714.txt", i, " ", k); write("b249715.txt", i, " ", n))); \\ Compute both A249714 & A249715 at the same time.

Formula

a(n) = A249695(A249715(n)).