A332129
a(n) = 2*(10^(2n+1)-1)/9 + 7*10^n.
Original entry on oeis.org
9, 292, 22922, 2229222, 222292222, 22222922222, 2222229222222, 222222292222222, 22222222922222222, 2222222229222222222, 222222222292222222222, 22222222222922222222222, 2222222222229222222222222, 222222222222292222222222222, 22222222222222922222222222222, 2222222222222229222222222222222
Offset: 0
Cf.
A138148 (cyclops numbers with binary digits),
A002113 (palindromes).
Cf.
A332119 ..
A332189 (variants with different repeated digit 1, ..., 8).
Cf.
A332120 ..
A332128 (variants with different middle digit 0, ..., 8).
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A332129 := n -> 2*(10^(2*n+1)-1)/9+7*10^n;
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Array[2 (10^(2 # + 1)-1)/9 + 7*10^# &, 15, 0]
LinearRecurrence[{111,-1110,1000},{9,292,22922},20] (* Harvey P. Dale, Jun 25 2020 *)
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apply( {A332129(n)=10^(n*2+1)\9*2+7*10^n}, [0..15])
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def A332129(n): return 10**(n*2+1)//9*2+7*10**n
A332118
a(n) = (10^(2n+1) - 1)/9 + 7*10^n.
Original entry on oeis.org
8, 181, 11811, 1118111, 111181111, 11111811111, 1111118111111, 111111181111111, 11111111811111111, 1111111118111111111, 111111111181111111111, 11111111111811111111111, 1111111111118111111111111, 111111111111181111111111111, 11111111111111811111111111111, 1111111111111118111111111111111
Offset: 0
- Brady Haran and Simon Pampena, Glitch Primes and Cyclops Numbers, Numberphile video (2015).
- Patrick De Geest, Palindromic Wing Primes: (1)8(1), updated: June 25, 2017.
- Makoto Kamada, Factorization of 11...11811...11, updated Dec 11 2018.
- Index entries for linear recurrences with constant coefficients, signature (111,-1110,1000).
Cf.
A138148 (cyclops numbers with binary digits),
A002113 (palindromes),
A077798 (palindromic wing primes),
A088281 (primes 1..1x1..1),
A068160 (smallest of given length),
A053701 (vertically symmetric numbers).
Cf.
A332112 ..
A332119 (variants with different middle digit 2, ..., 9).
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A332118 := n -> (10^(2*n+1)-1)/9+7*10^n;
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Array[(10^(2 # + 1)-1)/9 + 7*10^# &, 15, 0]
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apply( {A332118(n)=10^(n*2+1)\9+7*10^n}, [0..15])
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def A332118(n): return 10**(n*2+1)//9+7*10**n
Showing 1-2 of 2 results.
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