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A077274 Differences between two successive powers of a prime but not a prime (A025475) in more than one way. 0
4, 7, 17, 408, 792, 912, 1608, 1848, 2472, 2912, 3192, 3288, 3432, 3528, 4008, 4080, 4920, 5160, 5208, 5928, 6072, 6792, 6888, 7080, 7512, 7728, 7800, 8520, 8832, 10632, 10848, 11400, 11880, 11928, 12792, 13200, 13440, 13560, 14280, 14640 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..40.

EXAMPLE

4 = 8 - 4 = 125 -121, 7 = 16 - 9 = 32768 - 32761, 17 = 49 - 32 = 81 -64 = 529 - 512, etc.

MATHEMATICA

pp = Sort[ Flatten[ Table[ Prime[n]^i, {n, 1, PrimePi[ Sqrt[10^16]]}, {i, 1, Log[ Prime[n], 10^16]]]}]]]; l = Length[pp]; b = Sort[ Take[pp, -l + 1] - Take[pp, l - 1]]; Union[ b[[ Select[ Range[375], b[[ # ]] == b[[ # + 1]] &]]]]

CROSSREFS

Cf. A025475.

Sequence in context: A098091 A319782 A057450 * A292850 A080650 A276187

Adjacent sequences:  A077271 A077272 A077273 * A077275 A077276 A077277

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, Oct 31 2002

STATUS

approved

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Last modified June 1 00:27 EDT 2020. Contains 334756 sequences. (Running on oeis4.)