A249714 - OEIS

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

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OFFSET

1,3

COMMENTS

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

LINKS

Table of n, a(n) for n=1..29.

FORMULA

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

PROG

(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.

CROSSREFS

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

Cf. A007283, A249439.

Sequence in context: A370900 A069891 A190118 * A250177 A333002 A333000

Adjacent sequences: A249711 A249712 A249713 * A249715 A249716 A249717

KEYWORD

nonn

AUTHOR

Charles R Greathouse IV & Antti Karttunen, Nov 04 2014

STATUS

approved