A168091 Slowest increasing sequence of alternatively cubes and squares with common neighbor digits.

1, 16, 64, 441, 1331, 1369, 9261, 10201, 10648, 80089, 91125, 501264, 4019679, 9006001, 10077696, 60000516, 60236288, 80013025, 500566184, 4000056516, 6008715432, 20000182084, 40036787461, 100000147984, 400152624409

Offset

1,2

Comments

No term ending in zero is allowed.

Links

Table of n, a(n) for n=1..25.

Example

1 (cube), 16(square): common neighbor digits = 1,
16(square), 64(cube): common neighbor digits = 6,
64(cube), 441(square): common neighbor digits = 4, etc.

Maple

A168091 := proc(n) if n = 1 then 1; elif n mod 2 = 0 then pdig := op(1, convert( procname(n-1), base, 10)) ; for b from 1+floor(sqrt(procname(n-1))) do a := b^2 ; adg := convert(a, base, 10) ; if op(-1, adg) = pdig and op(1, adg) <> 0 then return a ; end if; end do ; else pdig := op(1, convert( procname(n-1), base, 10)) ; for b from 1+floor(root[3](procname(n-1))) do a := b^3 ; adg := convert(a, base, 10) ; if op(-1, adg) = pdig and op(1, adg) <> 0 then return a ; end if; end do ; end if; end proc: for n from 1 do printf("%d, \n", A168091(n)) ; end ; # R. J. Mathar, Jan 25 2010

Crossrefs

Cf. A167994.

Sequence in context: A230970 A352738 A061449 * A181208 A175209 A141840

Adjacent sequences: A168088 A168089 A168090 * A168092 A168093 A168094

Keyword

base,nonn

Author

Zak Seidov, Nov 18 2009

Extensions

Corrected from a(10) on by R. J. Mathar, Jan 25 2010

More terms from Jon E. Schoenfield, Jul 17 2010

Status

approved