A373621 Expansion of 1 / ( (1 - 25*x^5) * (1 - x/(1 - 25*x^5)^(1/5)) ).
1, 1, 1, 1, 1, 26, 31, 36, 41, 46, 676, 881, 1111, 1366, 1646, 17576, 24281, 32386, 42016, 53296, 456976, 658806, 916411, 1238666, 1635071, 11881376, 17706456, 25462936, 35569066, 48496846, 308915776, 472880356, 698851961, 1003283216, 1405555496, 8031810176
Offset: 0
Keywords
Programs
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PARI
a(n) = sum(k=0, n\5, 25^k*binomial(n/5, k));
Formula
a(5*n) = 26^n for n >= 0.
a(n) = Sum_{k=0..floor(n/5)} 25^k * binomial(n/5,k).
a(n) == 1 (mod 5).