A374101 -id:A374101 - cp's OEIS frontend

A380713 Lesser of twin self primes, i.e., smaller member of the pair of self primes differing by 2.

3, 5, 18521, 19421, 39827, 44621, 49121, 57221, 59627, 65927, 84221, 86627, 129221, 139121, 149627, 153521, 172421, 182927, 207521, 209927, 231821, 238727, 251621, 254927, 264827, 274121, 277427, 289127, 308927, 317321, 319727, 321821, 327827, 329627, 330821

Offset: 1

Shyam Sunder Gupta, Mar 27 2025

Shyam Sunder Gupta, Table of n, a(n) for n = 1..3683
Shyam Sunder Gupta, On Some Marvellous Numbers of Kaprekar, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.

Cf. A003052, A001359, A374101, A380715.

A382380 Greater of twin self numbers, i.e., larger member of the pair of self numbers differing by 2.

Original entry on oeis.org

3, 5, 7, 9, 110, 211, 312, 413, 514, 615, 716, 817, 918, 1111, 1212, 1313, 1414, 1515, 1616, 1717, 1818, 1919, 2112, 2213, 2314, 2415, 2516, 2617, 2718, 2819, 2920, 3113, 3214, 3315, 3416, 3517, 3618, 3719, 3820, 3921, 4114, 4215, 4316, 4417, 4518, 4619, 4720, 4821, 4922, 5115, 5216, 5317, 5418

Offset: 1

Shyam Sunder Gupta, Mar 23 2025

The number of twin self-numbers up to 10^n (for n > 2) is 9 * 10^(n-3) + 4. This has been verified up to n = 10.

Shyam Sunder Gupta, Table of n, a(n) for n = 1..9004
Shyam Sunder Gupta, On Some Marvellous Numbers of Kaprekar, Exploring the Beauty of Fascinating Numbers, Springer (2025) Ch. 9, 275-315.

Cf. A003052, A374101.

a(n) = A374101(n) + 2.

cp's OEIS Frontend

A380713 Lesser of twin self primes, i.e., smaller member of the pair of self primes differing by 2.

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