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A Colombian mathematician known for Recamán's sequence. The primary sequence record cites his 1991 correspondence; an institution-hosted interview independently identifies him as the mathematician and educator.^{[ref] [ref]}

Verified Spanish-language identity page: es.wikipedia.org/wiki/Bernardo_Recam%C3%A1n_Santos. An exact usable portrait URL was not established in the bounded Commons/Wikipedia and institutional-source check; the report records that gap without inferring that no portrait exists.

The first three subtractions are negative or return the already-seen zero, so addition is used. The fourth subtraction gives a new positive two; the next subtraction is negative. Thus $r(1),\dots ,r(5)=1,3,6,2,7$. These are the initial terms of Recamán's sequence.^[ref]

The integer sequence proposed by Bernardo Recamán Santos starts at zero. At step $n>0$, subtract $n$ if the result is positive and has not appeared before; otherwise add $n$. The commonly written nonnegative version gives the same sequence because zero is already present. The initial values are $0,1,3,6,2,7,13,20,\dots$. The addition branch can repeat a value: $r(20)=r(24)=42$. Avoiding a repeated subtraction is therefore not a global injectivity condition.^[ref]

Since $r(n)\le r(n-1)+n$, induction gives $0\le r(n)\le n(n+1)/2$. A prefix scan needs only constant extra storage but can take quadratic membership work. A bitset-style bounded membership table makes each lookup constant time, while its allocation cost depends on the chosen value universe. This separates the number of generated terms from the range of possible stored values.