55155: Near Repdigit Palindrome 55..55155..55

First few terms (base 10): \[[5^*15^*_7]_n=\{1,257,13809,684913,33618401,\ldots\}\]

First few terms (base 7): \[\{\text{1},\text{515},\text{55155},\text{5551555},\text{555515555},\ldots\}\]

General Formula:\[[5^*15^*_7]_n={35\cdot7^{2n}-24\cdot7^{n}-5\over6}\]

Equivalent Patterns: (none)

Table

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